OK after a year of jerking around,I finally have the cash to make some improvements on my car. Just wanted opinions on a couple of mods. I have an all original 4 spd 80 Z28 with 19K on it. The LM1 is only rated at 190 HP and 290 TQ. Last June, by swaping in a pypes exhaust with an X-pipe and V-Force mufflers, I ran a best 14.90. I don't want to get too far from the originality of the car, and have very limited expierence and funds for hotrodding but I don't want a slug either.
By swaping in my purchased ZZ4 intake, Comp 268H cam, going with 355 gears instead of 308's and porting the heads, how much of a HP increase should I expect, and would it take me into the 13 sec. range? Also, any tips on selecting a good mechanic to do the work? Thanks. Mike.

rather than porting, I'd spring for a set of aftermarket heads. Dart iron heads are great at around $700, edelbrock alluminum's are good to at about a grand.

I think with the proposed upgrades you will end up in the very low 14 second range...you might just squeek out a very high 13 with some good sticky tires and some aggressive driving. The car will also be a lot more fun to drive and remain very streetable.