ok ive got a 87 305 roller motor that iam rebuilding and i wont to use a 87 350 crankshaft because it is enternal balanced i know thay both have the same storke so are thay the same thanks for your help

 

They are both the same "almost". The 350 has heavier counter weights so you would have to have them cut down or drilled to be balanced correctly.

FWIW a lot of the guys here locally use 305 cranks in their 350's. With light aftermarket pistons and rods it is easier to balance with a 305 crank. With a 350 you have to remove a lot more material for the balance.