I Have A 98 C5 With Stock Heads With A Lunatti Cam 221/221/558/558 W/112 Sep And Many Boltons. I Have Stock Heads Now And Have A Friend Who Has 317 Off A 2004 6.0 Litre For $300. Which Heads Makes More Sense To Go With The 243 With An Average Price Of Around $700-800 Complete Or These Heads And Mill Them 25-35th To Get The Compression...........also What Is The Max You Can Mill Without Having Piston To Valve Issues And Deck Thickness And Intake Ports Not Lining Up...thanks Kevin