Will it fit? Yes, a 305 crankshaft *generally* fits into a 350 block. Both are based on the same basic small-block Chevy architecture. However, there are a few important caveats:
* Rod Journal Size: While the main journal size (the diameter of the crankshaft where the connecting rods attach) is the same, the *rod journal diameter* might be slightly smaller on a 305 crank than on a 350 crank. This means the connecting rods from a 350 may need to be machined or replaced to fit the 305 crank. Using 305 connecting rods would be necessary for a perfect fit.
* Stroke: The 305 crank has a shorter stroke than the 350 crank. This will result in a smaller displacement engine than a standard 350. You're essentially building a slightly smaller displacement 350. This change needs to be taken into account for piston selection.
* Other potential issues: While rare, there could be minor differences in the crankshaft counterweights or oiling passages. Carefully inspect both components before assembly.
In short: It *will likely* fit, but it requires careful consideration and possibly some machining to ensure proper operation and prevent damage. Consult with a qualified engine builder before attempting this swap to avoid costly mistakes. You'll need to pay close attention to the connecting rod fit and select pistons appropriately for the 305 crank's shorter stroke.
