To Stroke or not to Stroke?

[Moxie]

As long as you have to replace the crank and rods, I vote for the 331. Unlike a 347:

The block doesn't need to be machined for clearance. It can be assembled just like a 302.

The piston pin doesn't intersect the oil ring.

Better rod ratio, so less lateral load on the piston.

IMO, you'll get better durability out a 331 than a 347, and almost the same power. You may want to consider porting the P heads.