rzepka,
If you've got the cash to have Kauffman build you a 500HP motor - then I agree with Cliff & Alex. Put $300-400 into upgrading your fuel system and never worry about it again. Having said that, my '66 GTO with a 462 & about 400HP has run a best of 8.5sec in the 1/8th with a
completely stock fuel system. It has plenty more in it & I expect to see high 12's in the 1/4 in the spring and the fuel system has not been a limiting factor.
http://kurtspontiac.homestead.com/TimSimpson66GTO.html