how tough to put 318 in '64 Dart GT with Slant 6?

Currently has a tired slant 6 (original). I can get a 318 from a '77 D100, but I want to know if it'd be a nightmare to shoehorn it in. Either way I'm going to be rebuilding an engine. I don't know which trans it has in it, all I know is it's a slushbox. Any chance I can bolt up the 318 to the trans? What am I looking at regarding steering column, exhaust (headers or manifolds, etc. I don't think it has power steering. I'll know more when I pick it up.

Thanks.