Which hydroboost unit for a swap?

[B_derK20]

I'm getting ready to dump the vaccum assist brakes and swap over to a hydroboost setup, but I'm not sure which of these 2 units I want. The first unit was pulled out of an '84 K20 with a 6.2 and the other unit I have came from a '78 C30 with a 350. I got the pedals and everything in between from both trucks, and it looks like it should be a straight-foward deal. The master off of the C30 is larger than the one from the K20, but the hydroboost itself from the K20 looks to be in a little better shape. Can I swap master cylinders from one to the other or will both setups be the same? The truck receiving the swap is my '83 K20.

Thanks in advance!