Small Block & Big Block Chevy Specific - crankshaft

Is the crankshaft of a 4 bolt block identical to that of a 2 bolt? Specifically, the rear of the crank, where it goes into the rear main seal. diameter is not the question, it is length. I am having issues with my clutch fork pivoting and hitting the pressure plate. Questioning if the crank is longer, therefore changing the pivot point.

there should be no difference

They are identical as long as the rear main is the same style (87+ is 1 piece while pre 86 is 2 piece).

thanks guys.

You might have the wrong throwout bearing in there. I know there is a short one and a long.