I have been searching high and low for this info. I read the article here and it really helped out alot. I want to port the heads and run Crane's 2030 or 2031 cam and their springs, 1.6 pedestal mount rockers. I don't want to change to studs. Does anyone have these part numbers (1.90/1.60 valves) and maybe where I could get them? If I can't afford the machine work can I run 1.84/1.54 from the 351 heads in standard length? Thanks a million for any and all help.