right now i'm building a 406 for my 68' camaro,the 327 is a bit tired. the 406 must be streetable and must run on pump gas . so i'm going to have around 10.0:1 compression and hoping for around 440hp and 480tq. I have set of 906' vortec heads. i need to know how much machine work i need on the heads. i thinking of running voodoo cam with 227/233 dur. with 489in/504ex lift. do have have open up the valve spring pockets? and do i need to mill the guides down a bit? and also would it be wise choice to cut the heads out for 2.02/1.60's,is there major flow increase on these heads with bigger valves. much help appreciated!