Will a Chevy 350 crank fit in 305 and what it make the engine with stock bore ofcourse?

No, a Chevy 350 crankshaft will not fit directly into a Chevy 305 block without modifications. While both are small-block Chevrolets, the 350 crank has a longer stroke. This longer stroke means the crank throws will interfere with the block's cylinder walls. You'd need to bore the block significantly to accommodate the longer stroke, and even then, it might not be feasible or a wise choice due to the potential weakening of the block. Ultimately, it's not a practical swap.