I machined mine myself and I took .015" off each head. Haven't had any problems with the intake lining up or any valve clearance problems. You could go more as long as you have the intake manifold machined as well to make up for the narrowed V angle. Just remember to leave about .100" clearance between the piston and the exhaust valve at full lift. Intake valve should be around .080" clearance at full lift. You should also make sure that your crushed gasket thickness of your new gasket isnt thicker then your old one because if it is you have to take the difference out of the head aswell to come up with your new CR. I also have some pictures of what the RA finish should look like.
Would'nt an easy 75-100 shot of nitrous cost less, and give you better power than the cost of labor and time of the head work is worth? It just seems like a lot of work for a small compression differance. How much power do you get from this modification Red Devil? Also,.. did you do the machine work yourself? That could save you alot of money.
I go to school at The University of Northwestern Ohio for HP technologies. I did the work myself because i already had to mill the heads for gasket sealing and to ensure a flat surface. I did the math and with the amount of material I removed and my custom weisco pistons i ordered at 8:1 compression I came up with 8.56:1 total CR. With the extra boost i plan to run reaching 15-18PSI, my Cams, Fuel injectors, nitrous, the porting work, ect. I hope to make a good amount of power. If you already have to mill the heads then there is really no extra cost in removing more material. i would post a pic but im not sure how to do it on the forum.
Like I said i have cut .015" off the heads and .010 off the block. I haven’t ran into any alignment problems with the amount that i took off but if you removed more then i have its not real difficult to fix. You just need to take the material off the intake manifold. Make sure to get the proper RA finish on your head as well to get the best possible seal from your head gasket.