I just put together a 383" with Eagle SIR rods which had 3/8" bolts. Crank was 3 3/4" stroke, i had to grind the block to clear the bolt heads in several places near the bottom of the cylinders. I would think a 4" crank would be next to impossible without lots of grinding and weakening the block at the bottom of the cylinders.
JMO
Zip.