Stroked 340 vs Stroked 360

Depends on the 340 block. If you can score a good deal on a 340 TransAm block, do so. This one has thicker webs to allow for 4-bolt mains.

One of the problems I have with the 360 vs 340 main discussion is that, at least in showroom trim, we never got to see a high compression 360 4 bbl with a forged crank. They also changed bore and stroke. So we have no good basis for comparison between the two in a factory HP configuration.

Over in the Chevy camp, the discussion is pretty much settled. The 327 was known as a high-winding runner. The bottom end was suspect. When Chevy came out with the 350 in 1967, it was essentially a stroked 327 with LARGER main journals. (FWIW: Chevy continued to use the 327 in 68-69 models but with a large journal crank.) This provided more power but also cleared up a lot of the bottom end problems.

Based on the Chevy experiences, I would think that a 360 would work better. However, the small journal LA does not have the gimpy bottom end reputation that the original mouse motor had, it may not be that big of a deal. Given that the upper end will be the same and cranks are the same except for main size, the ability to rev is going to be determined by the stroke and the balance that is necessary for the piston/rod combination that is used.