Im new to this scene but wondering if I can get some help I have a stock Bottom end lq9 6.0 with ported n polished milled .030 243 heads ls7 lifters upgraded valve springs fast 102 intake manifold with a comp cam 235/243 duration 621/624 lift just wondering if this will be a good setup to get the most out of the 6.0 without ptv clearance issues or is there a better setup to go for to get the most out of my lq9 willing to pay go big or go home !

 

That duration is at the limits with flat top pistons with no valve reliefs and milled heads. As always, best to check. You may can move the cam around and squeak by but, I think you will come up closer than one would want.

 

My 6.0 build has a 238/246 duration cam with 823 heads that weren't milled and the pistons are 12cc domes. My closest P-V on the intake and exhaust valves without a head gasket in place was 0.260 and 0.158 so I could have milled these heads .030 and still be okay. I think you'll be fine but always verify the installed camshaft matches the cam card and you measure P-V.

 

The Lobe Separation Angle, LSA, is more of a determining factor on clearance than duration alone. IIRC, a tighter LSA (more overlap) will reduce clearance, and a wider one will increase it......

 

Yes, LSA combined with duration are major factors concerning valve to piston clearance. He didn’t mention what LSA his camshaft had.
Best advice is always check.