My situation is somewhat similar to yours. When I got my car back in 2000 (sold it in '88) I discovered it had '67 closed chamber heads which made me happy as I always had wanted a set. The problem was the car would not run on ANY grade of pump gas without severe pinging. When I took the car apart to do some much needed freshening up I disassembled the engine down to the short block and discovered to my amazement that the reason for the pinging was a set of TRW domed 11:1 (or better) forged race pistons (# L2293 - .030 over). I also noticed tell tale sings of balancing on the bottom end (grinding on the rod end caps, etc). Not wanting to spend the $$$ for a new set of pistons I went with a set of open chamber 452 heads which were fitted with 2.14/1.81 valves, generous porting and a very mild milling (.010") to flatten the mounting surface. The final volume size is 88cc. We figured that the compression ratio is now somewhere around 10.5:1.
Knowing that I needed a somewhat healthy cam to bleed off some of the cylinder pressure I opted for the Comp XE275HL-10. Specs are 231/237 @ .050 with .525" lift and a 110 degree c/l (with my 1.6 roller rockers the lift is up to .560"). It pulls between 9.5 - 10.5 in. of vacuum at idle. Now that everything is set up it runs like a champ on 87 octane fuel. Since your setup is a bit wilder on the compression I am concerned that you may not be able to get by on any grade of pump gas without a lead additive such as Max Lead 2000. Also of deep concern is the fact that you have shaved a lot off your heads, (I hope you also took off .0125" of material on the intake mounting face for every .010" removed from the combustion chamber side also or else your intake manifold bolt alignment will be hosed), which will indeed reduce your piston to valve clearance. You will most likely need valve notches in the pistons if you are running flat top pistons. The L2293 TRW's I have are designed for big valve lifts so if you are running this piston you should be ok with a cam in the .500" lift range. Also important to note is that it is not just lift that will cause piston to valve clearance problems in the BB Mopar engine. Duration also plays a big part in this as well. Back in the day, Chrysler's engine bulletins recommended that valve notches in the pistons were mandatory with the use of any cam that had an advertised duration of greater than 286 degrees. These days duration is measured at 0.50" lift so you should consult with a cam manufacturer's tech line to see what they recommend for your setup. Also keep in mind that the heads will have to have the valve guides machined down so that you can run a higher lift cam. You'll also need teflon seals for the valve guides.
I'd highly recommend calling Lunati, Comp and Hughes Engines to see what they might be able to do for you in terms of camshaft selection. The tech line guys are pretty sharp and should be able to help you make the best choice.
Check out this article on a 383 build - it might help some:
http://www.hotrod.com/techarticles/engi ... index.html
