I'm partial to wagons, but the best looking Volvo (thanks to Bertone) was the 780 coupe....
They're a bit rare, but they can be found. And V6 ones are all begging for an engine swap anyway.
I come from a Volvo family, as my dad is the only owner his 1800 has ever known. I really wanted to get a 780, but I found a lot of issues beyond the difficulty in finding a decent example to start out with. There seems to be some issues finding some parts for them. The engine stuff is common to other late 80's very early 90's Volvo, but some of the mechanicals, interior, and exterior parts were specific to the 780. Because they were a very limited run vehicle, it is hard to find used stuff. What is out there is priced very high for anything specific to the 780's as a result.
I would say go for a 240 if you want to do a V8 swap. At least here in Cali, if you look around hard enough you can find a decent example that is rust free and in decent condition. I don't know if there are any LS1 kits, but I know there are some for the Ford 5.0's and such.