The fuel pump is easy to tell, if it's remotely correct.... the long pump has the 1/4 inch fitting for the return line (3 lines total, 1 out, 1 small return, and one 3/8 inlet) whereas the short pump only has two total lines, the one that threads into the body to the carb, and one 3/8 inlet barb.
That and the body of the "can" of the pump is about 1 1/2 inches on the short pump, and about 3 inches on the long.
If you're running a performer intake, you're probably running a Holley too? You'll be better off making your own lines anyway, as the performer is taller than the stock intake.
