Getting ready to fire up the 512 stroker and need some in put on what length plugs and what number and what brand . Has Eddy performer alum heads and is 11/1comp with 509 purple cam and M1 intake with 950cfm proform with msd ign and tti headers .Roller cam will come when $$$$ alow.what kind of power should I make??Its a four speed car.with 4:10gears @3800lbs..these heads are angle plug and have a deep thread for the plugs..I tried a j12y and it only went in 1/3 of the way..plugs would be fireing inside about 1/2 inch inside the threads...HUH ????