wanted 906 heads or any 383 parts

......... The magnums had better valve springs [single with dampner] 10.0-1 comp instead of 9.2-1 had what was refered to as the road runner cam 450+458 lift 268+284 duration on a 115 centerline...the 440-6 had the exact same specs with 3 attaching bolts ........kim.......