Slant Six to Big block Engine swap in a 74 dart sport.

Well thats a relife I might get to keep the power steering cause i'm not exactly built like rambo .I got the trans mission idea figured out I was either gonna buy a 727 from a guy I work and seems like every big block mopar around here has one of his trannys in it including one hemi charger but I think he builds em to stock spec. Would I be better off buy spending the 1200 on a beefier from TCI, Another thing I was thinking about the ignition is already set up from electronic is there a way I could just get a hei distribtior or would I still have to get a hei conversion from proform or msd.And as for the rear it is a 7.25 I found a couple b-bodies 8.75 cause I think there 1.8 wider then a-body and I was thinking about bringing it to drive line specialties to have it narrowed up or should I avoid that idea.And I was going to run ladders bar on it with traction bars.Thanks again guys its been very helpful so far I was kind iffy about a big block in it but the more I read I've realized I've had worse idea lol.