your assumptions are only partially correct Mike. the numbers are not as disparate as you would be led to believe, and some things are more wants than requirements. I understand the wants but you're tilting things a bit. For the list of stuff you're talking about doing to a volvo engine, including the parts you already have, we're not talking about a 400hp 16v.. if all you wanted was 400hp you can do that safely with ~$1k in rods and pistons, and a couple hundred in machine work, a nice header, and a nice intake manifold. with an engine that may weigh 430lbs (a b230ft is said to be around 375ish, add the turbo and manifolds and head weight difference) fully dressed bolted to a transmission that weights what, 100lbs? say 150. so.. almost 600lbs of engine and transmission.
An iron ls engine fully dressed tips the scales at just over 500 by itself, and that 4L80 with an oem converter is somewhere north of 200. so you're at least 100 lbs up on the front end. If we want to keep the comparison truly fair, you're not going to be able to drop that tired old truck engine in the car and slam down 400+whp. Most of your truck motors (and a cursory google search for the specific one you've referenced) belt out between 285 and 315 crank hp, which.. is boring. I don't care what any of the other v8 guys say, that junk is weak as F, and they're known to float valves on the stock cam and springs well before 6k. That would be an absolute bag of **** in the nice car you've put together.
So you need a cam. OEM grinds can be had for 150ish from summit (yawn, btw), you'd need new springs to go along with that, and if you're going to be in there doing that, there's various preventative maintenance items that suddenly come in to play. So, let's say you do the norm, get a new timing chain, oil pump, damper, and front crank seal.. that's another ~$250ish for the moderate stuff.. So, now you've got something that may be up around 400 crank depending (if you sack up and get a manly man aftermarket cam, you might as well just get the whole kit, and those run around $700). your power to weight ratio is still hosed in favor of the 16v, and you're still dragging along a completely stock 4L80e (assuming it's actually in good shape to begin with).
to put a sporty converter in that 4L80e you'll be doing good to get a reputable unit for less than $600, and if the trans is suspect or shot, that's another $750 right there (but, on the upside, you'd have a transmission that's fairly bulletproof up to around 4 digit power numbers, bonus).
To add insult to injury, you look at the car tomorrow and think, man it's not bad, but I'd like another.. 100hp and it'd be just right. Your options on the v8 are fairly limited at this point, you can spray it, or you're sinking bucks into far more than 100 more hp. With volvo setup, you simply turn the boost up.
And you're still lugging around in a sporty little car with a giant GM automatic. to have the same fun level that you'd get with a manual trans behind the 16v, you'd need a manual trans behind that v8, and there you're talking similar numbers to what you quoted for the 16v setup,
If you want some real numbers I've got some real numbers, and you can check em in the 940's thread..
16v 2.3 setup in the 940 set me back around $2500 (no fancy pistons or machine work though), add 700 or so for the ms3x with the knock option and the dual vr decoder for traction control and we're at around 3200. Full weight wagon trapped 113mph, with my fat ass in the driver's seat you're talking about a race weight of around 3500lbs if not a little bit more.
the 5.3 setup in the 940 so far.. well, it's been more than I expected, but the big dollars:
$1200 for engine w/accessories (and then I had to turn around and get different accessories because most of them didn't fit and the starter was junk, but I'll give you the benefit of good luck) (but it's alu, so -75 to 80 lbs off the nose)
$400 for a known bad 4L80e transmission (turns out it probably had a solenoid that popped out of the vb, but it was sold as a core so it was treated as such).
$775 shipped for the Jake's stage 2 kit-which is not much more than any off the shelf 4L80e kit with a couple little bits you could get separately if you'd like, but the price comes out the same.
$1200 for a stage 5 tripple disc converter that will allow me to lock up anywhere any time (minus $500 for that option if you don't want it)
$800 for a comp cam, springs retainers pushrods crank bolt and ls9 head gaskets (believe they lower the CR just a tick). take off ~$80 or so for the hg if you think you're going to get it done with the heads on
I think I'm close to $1000 for incidentals with summit (lines, fittings, fpr, flex plate, spacer, crank bolts, stuff like that)
$500 for a water pump, oil pump, timing chain, chain damper, front gasket, pan gasket front and rear seals.
and I still haven't gotten the driveshaft, and I'm not including the new wiring harness for the MS that I already had, or the microsquirt I had to buy to control the transmission, the accessories that were bought, the free intake manifold, and a couple hundred in other misc items sourced from non-major retailers.
Understand, I'm not hating on the v8 swap, but to have good results commensurate with the level of work already invested in the car, you're not going to just slap some worn out transport engine in there and ride out.. all that would get you is a pickup truck in a volvo shell.. not much different than what you've got in there now except you've got an auto and it may be as fast as a BPU'd turbo volvo.