got some parts mixed up

Lol this is exactly why stock cars are worth so much more than chopped up ones...

The big problem with cam caps is that they serve as the bearing surface. At the factory, the caps would have been bolted into place and then line bored/honed so each cap really does have a unique location.

Assuming you're building a Romeo with ladder-style caps you might consider trying the following: Lay a cam in place, put some Plastigage on each cam journal and bolt one of the cap caps in place. Remove the cap, measure the 'gage and jot down the numbers. Repeat with another cap and then compare the numbers. Use the cap that gives the most favorable and consistent clearances.