340 X head advice

I like the Edelbrocks, and locally here, it cost only $110 to have the seats touched up (for valve centering) and a quick Serdi cut below the seats.

But you are not just going to slap them on your short block and go without examining the compression ratio changes. Your real static compression ratio with L2316F stock replacement forged pistons (which I assume is what you are planning) and .039" thick head gaskets is going to be around 9.6 with the stock heads. If you put on the Edelbrocks with the 'open' chambers, then your static CR is going to jump up to around 10.4 with .039" thick head gaskets and 10.1 with .050" thick head gaskets. That is getting into 'CAUTION' territory for open chamber heads and that size of cam, but at least the AL heads will help.

With the Lunati '703 cam, DCR with the 65 cc 'open' Edelbrocks (PN 60179) and the thicker head gasket, the dynamic CR (DCR) will be 8.2 with the cam installed at the factory ground 106 ICL. Your elevation in Clayton is low so you will get the full DCR number, and that will mean you need to run pump premium and will have to be careful in tuning carb and ignition advance to stay away from detonation. Don't just slap this thing together and not carefully check ignition timing all that; and an running an AFR gauge would be wise for that DCR, IMHO. I surely would not go with any smaller cam as that would push DCR up even more. On the good side, that combination will be very torquey on the street, ought to work with the stock TC, and still breath well up at higher RPM's.

I personally would not go with those pistons you have selected, but use ICON FHR IC9975 forged flat tops and then use the closed chamber Edelbrocks (PN 60779). With shave of .010" on the block to get those pistons to zero-deck and the block trued up, and a .039" thick head gasket, you can get the quench effect going and that will further help fight detonation. The SCR will be 9.8 and the DCR will be 8.0; the whole combination is going to be less prone to any detonation. (I fact I expect it would take being pretty sloppy to do so.) The only downside of the ICON's is that you need to work on the engine balance, which involves some more $$. So all of this does involve probably $500-$700 more overall, but then engine is pretty 'friendly' to being a bit off in tuning.

Regardless, with any of these combinations above, IMHO you need to become familiar with tuning and ignition timing and cam timing topics, if you are not already there.