x-cam clearance

Alright so my situation is a little different than the typical clearance questions regarding the x-cam. I have a friend with a 306 bottom end who bent the #5 connecting rod when a lower intake manifold gasket failed and sent coolant into the combustion chamber. This happened while he was in the process of selling the car so to help out I agreed to help him replace the rod. The motor is out on a stand and we are in the process of finding a rod to replace the bent one, but we are deciding what to do with his AFR 165's. Going into this project I let him know my interest in the heads so we are planning on swapping my iron gt40's and tubular gt40 intake manifold, for the 165's and edlebrock rpm manifold. My problem is that the 306 has an x-cam and I really do not want to pull my heads off if I am just going to find out there are clearance issues. I am not sure what brand pistons are in the 306, (they have a lightning bolt on the side), and I'm hoping the gt40 irons will work so we can get the car sold. Another option is to pull the x-cam and put my stock cam in, but in the end we want to sell a good running car and keep the 165's for ourselves. What do you guys think will be the best decision?

sorry for being uncelar... but I plan on putting the 165's on my shortblock and putting the gt40 irons onto the 306 with the xcam. So the quesiton is, will the gt40 irons go onto the 306 with the x-cam without clearance issues. I assume if valve size is all that matters, this should work since the gt40's valves are smaller (i think). Any thoughts?

I guess I will go ahead and pull my car apart tomorrow and put the gt40's on the 306 block (the one with the xcam), since I am somewhat convinced everything will be fine. I've heard of the clay method before, but I figured since the 165's had no problems clearing it can be assumed that the gt40's will have an allowable p/v clearance.