Johnnypac

I have a 2007.5 Chevy Silverado Vortec max. Pulled the engine which was cracked. Built an l76 with truck Norris cam, upgraded springs, trying an upgrade. Block and heads were done by Machinist.

when I start the engine, there is always white smoke on Startup and the idle surges until closed loop. I brought it back to my tuner on three occasions and he says it is not the tune. He told me to bring it back to the mechanic and have the white smoke on Startup issue fixed first and then he would tune it. Mechanic says it is in the tune.
when it is warmed up, closed loop, it drives great, No smoke, No surging and a lot of hp!
new upgraded driver side valve cover
Tried an oil catch can, no luck
mechanic did a compression test and said cylinder number 8 was at 50, all the others were within 5 or 10% of each other at 100 to 110. He kept it for 3 weeks and did nothing so I brought it home and did a leak down test but found nothing.
not likely to be valve stem seals as the heads were just done

No seet smell, oil is clean, No bubbles in coolant overflow.
Maybe blown head gasket with 50 psi on number 8 but leakedown didn't show anything, not sure i trust that mechanic.
could this really be in my tune?

another mechanic mentioned taking off the K n N
Filter..... haven't tried that yet.

Input?