Seriously, you might try a salvage yard that has some really old cars or else an automotive museum. What are you going to put a straight 8 Buick in? They werent worth a hoot as a performance engine and had a real bad problem of breaking if you wound them up to anykind of a reasonable rpm.
I havent seen one of those since I was in high school (Class of 66).
If having all your cylinders in a row is your thing, I would suggest going with a big displacement I-6, like a 292 Chevy or 300 Ford.
They are both excellent engines, and would outperform that Buick with out even working hard to do it.