340 xhead spring shimming, height and pocket question(s)

I had planned to go thru it all with dial indicator. 340 Short block I just finished and wrapped up while I work on heads.
I want to mock everything up, but can I reuse the MP head gaskets?
Thanks
Steve
It's a mechanical cam. Don't forget to add valve lash. Also if coil bind is going to be close I like to measure actual coil bind of the springs. Then the actual lift of the valves with a dial indicator. All this mocked up with the valve springs you are using and on the engine it's going on. I find that actual lift can be less than calculated lift due to deflection and geometry of pushrods and rockers. For me, if it's not close calculating is fine.