The 3.55 stroke was an MP 8 bolt crank and the rods were 6" aluminum MP parts as well. Rev'ed REALLY nice but to a lot of bore notching to clear those 318 bores for the fat aluminum rods. It was a 30k mile standard bore hydraulic roller block, with a solid that thing would have loved to rev to 8K with the right heads.

The point is you make you a 10:1 340-350 ish 318 motor without a lot of creativity, there's still a lot of those MP 3.51 or 3.55 cranks out there with 340 mains. Speed o motive sells a 360 crank based 350 kit. But then it's about as cheap to do a 4" 390