I've got Aussie heads and a CompCams 282S, a little more stout than the one you are proposing. I followed the formula proposed by Dan Jones, which yields 480hp, according to Desktop Dyno... I've got a Weiand Xcelerator, had the heads ported and flowed, the intake port-matched to the heads, and some other mods. I've got all the details in a file, e-mail me if you'd like a copy.
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Charlie McCall
1972 DeTomaso Pantera #3847 (for sale)
1985 DeTomaso Pantera GT5-S #9375
"Raising Pantera Awareness across Europe"
http://briefcase.yahoo.com/gt5s_1985