I have an '84 mark IV 454 block, using '66 396 stock heads. The problem is the block has the 4 extra coolant holes that is supposed to use fel-pro 8523 pt. the heads are older and supposed to use fel-pro 8180 pt-2. I am using the 8523 now and veh is overheating and spraying coolant out of the radiator cap after shut off. Waterpump, t-stat and radiator are new, Anyone think the h/g is causing this problem.  

I dont think that is your overheating problem, although the newer style heads and block that used the "three" extra coolant holes do a much better job at cooling the combustion chambers and exhaust valve area. You would benefit from changing to the newer style head from a cooling standpoint as well as the open chamber design of the later head. Your early style closed chamber heads dont breathe nearly as well due to exessive valve shrouding. Back to your question, how hot does it run? Is it pinging when under a load?  What vehicle is it in?  

runs 250 after about 10 minutes. with radiator cap off, and shut veh off after about 15 seconds I have a 2 foot gyser coming from the radiator. Was told there is a hot sopt in engine that when the engine shuts off and waterpump is not working, the coolant seeps into the cavity causing the boiling after shut off. Did notice that the newer style h/g has the corner core holes blocked off that are open on the older h/g's. Motot is in a 55 sedan. Not concerned about heads quality, the h/g's have different holes that are closed when compared to each other. Main ? is do i need a gasket to match the block or the head?  

The head gasket that will work with your combo has the two corner holes open. They blocked one of these holes on the newer style to force coolant into the three holes that you do not have.  

thanks, thats what i was thinking also. To bad i got to tear it apart again, especially after it just came out of getting painted