actually i was thinking about it today and i talked to my uncle and he said the 400 should bolt up to a 700r4...im doing ome research with that now... the 300 because my dad had an 80 chevy stepside pick that originally had an inline 6 in it with a 4 speed trans and id just like to follow his steps... just the trucks an automatic so i didnt really wanna cut a 2nd hole in the floor to give it a t5 from a camaro. for now im just looking around for the motor... im gonna rebuild it... give it bigger cam like my dad did with his...and for the cooling issues i might try the dual thermostat setup that chevy used with the 6.5 diesels post-97 hell at one point in time i thought i wanted to put a mack v8 in it lol