Here's what I know....
The simple search on your average parts warehouse produces the KYB gas-a-just shock (Part Number: KG4550) as the best thing available....probably because the 164 is a dead platform and no one updates their catalogs for them. A little cross referencing and it turns out that's the SAME part number used for the corvette from 63-82.
The question becomes; does it not stand to reason then that whatever else might be listed as a front shock option for the 63-82 corvette would also apply to the front of a 164? Say: the Bilstein B8 (Part Number: 24-184526)?
I'm all for finding out, but I have another question: Has anyone in here had experience between the B6's and B8's? They're both HD shocks, but the B8 is listed for adjustable ride heights. To be honest, I didn't even known Bilstein got that particular since everything anyone ever sells in a Volvo forum is "Bilstein HDs."
Which leaves me with the rears...nothing appears to cross reference fitment wise but other dead Volvo platforms (140 series). Reportedly, the only difference between the 240 and the 164 is the bottom bushing...otherwise same shock. IPD confirms that as they're still selling their old 240 Bilstein B6's (Part Number 24-002967) with new bottom bushings that'll fit the 164. Does anyone know if there's a B8 equivalent to that shock? I can't find a damn thing!