i recently purchased a set of ported heads and the cooant crossover linein the back was plugged with a pipe plug (metal threaded plug). do i need to remove these and run the crossover line or should i delete the crossover line altogether?

these are stock LT1 castings

 

I'm pretty sure that deleting the tube is not good. From what I have heard and read, that is an important part of the reverse flow cooling system.

 

That tube is an important part of the system, you can't run without it.