Another 302 Head Question

I see in your profile that you are now 18. So engine has sat for 5 years ? Was the engine just sitting on an engine stand or was it installed back into the truck back when it was " assembled ?" If it was installed back then, did you put any water in it ? If so it probably will need more than a head gasket set. So an engine shop inspected the motor and it was perfect ? What does that mean ? Did they do a compression check, oil pressure check ? Leak down test ? Did they remove the heads and oil pan and inspect the cylinder walls, pistons, bearings, cylinder head chambers, valves, deck and head surfaces ? Thicker head gaskets do not seal better than thin gaskets unless something is wrong with the surfaces you are trying to seal. The only time anyone uses a thicker gasket is when their headers are leaking. Usually because the header mating surface is not true and gaskets are easier, if they work. The more that you machine the head surface, the thinner the surface will be. The thinner it is, the more likely it is to warp when heated. Just like brake rotors that are machined too thin. Vibration when hot because there is not enough material to absorb the heat. Get an extra set of top end gaskets in case your "porting job " does not give you the results you were hoping for and you can put the good set back on. If you are determined to do the port job, remember that you can't put any material back that you take off and the most common mistake is going too far. Don't change the shape of the ports, just smooth out any casting flaws. Do not touch the combustion chamber. You will only lower the compression which will lower your HP. Do a port match to the intake and exhaust gaskets. Good luck and it takes many years to get the experience doing this stuff. You are still very young. Take your time. Get good tools, good service manuals and read a lot.