I think It may just be reversion them. Gonna have them re checked and see what happens. Just wondering if the new guide did not seal properly where salt is all stucvk around where they press through

+1.

It alwas was about 12.5 -1 fuel ratio not any leaner, timing was at 34 degrees

or if the timing was off the valve seats in a aluminum head can move..or you got bad gas that screwed them up..

Valves are not tuliped

machine shop that did the guide work said that the exhaust guides do not go through a water port and no tuliped valves so i thinking reversion is the issue. can anyone confirm thi,s that the guide does not go through a water port?

You need to talk to Foxwell Motorsports. He actually help develop the canfield head which is supposed to be really awesome. He can definitely help you with the head design question.
As far as the cam, you are probably experiencing reversion. Your cam LSA (lobe separation angle) should 112 to 116. Pending on setup.

were the exh seats pounded out ,if so the seats could be to soft

I'd be looking at the cam...

does canfield make a head for the gm 496