Question on TFS heads

[MEDIK418]

Well, I got the 89 back on the road and man it shifts nice. A little notchy but much better than before. Anyway, my question: My son called tonight and is about to buy a set of TFS heads for his car, The engine already has a Trick flow Track heat intake so he wants to do the same brand head. It has an F303 cam in it and he thinks the cam needs more compression. It already has 9.6:1 forged TRW's in it and I agree that the cam is too much for the engine but he likes the lope. He wants to raise the compression by shaving the heads before the install.
Does anyone know how much "shaving" will have to be done? What is the highest compression he could possibly go while still running pump premium? He's not sure what the chamber CC is but that's easily found. Have any of you done anthing like this and if so, can you shed some light for us?

Thanks for any input you can provide.
In case anyone here is confused, He is in Pensacola and the car is here and I'm trying to get it ready for him to take to North Carolina in a month or so. That's why all the long distance car building.