340 or 360
The 340 is a beast when you stroke it.. :!:
Here's the scoop. The 360's bore is slightly smaller than the 340's so the stroker crank gives you 408 cubes in a 360 block (standard bore) and the same crank in the 340 block gives you 416 cubes.
Bottom line, if you got the 340, build it. If not use a 360 and laugh all the way to the bank cause you saved some dough.
Heres a few dyno tests of these combos.
http://www.hughesengines.com/dyno_results/sb_stroker1.asp