[ER]

I have been beating my head against the wall trying to figure out where my horsepower went. '67 GTO 670 heads w/'71 block .030 over, performer intake w/1407 edelbrock carb, and 280 ah Comp cam with stock springs and rocker arms. Th400 trans. The motor was rebuilt in Dec 2004. I noticed what seemed to be a lack of low-end power immediatly. Mechanic suggested getting dist. recurved did that now I'm having to run almost 75* total timing in order to keep engine temp down. The shop who did the dist. said he gave my 30* mechanical. He said to go 10-12 initial, if I do the temp goes up instantly. Have asked mechanic if cam was degreed correctly and he is 100% sure it is.
I left the "original" torque conv in the trans and we didn't touch the rear end (2.93 gears). Before the rebuild it would light up the tires from a dead stop and catch it going into second. Now, only if on the right kind of pavement or if it's wet will it spin the tires.
I am thinking about roller tip rockers. Will this make any difference ?

Sorry for the long post but I have spent the last 7 or 8 weeks reading through the archives looking for answers and finally had to ask.
Thanks,

ER