i absolutely need a ney transmission for my 72 chevelle. it has a 454

(i don't know witch one caus it ain't matchin number). the car is originaly autamatic
so here si my dilemme: should i get a th-400(ans buy extra goodies like posi high gear differential), get a th-700, or make the step to the munci
i know if i choose this option i will have tou get a bellhousing, a chutch kit, a shifter kit, and a clutch pedal assembly... would it worth??? this is why i'm making this post
thx
sory for my english i'm from montreal