(Newbe) 273 to a 340 and tremec 5speed swap.
i think he said that the front suspension and brakes were already done. but as to what's on there? who knows!
100% on the rear end swap. unless you spend beaucoup bucks it's hardly a drop in, and even then there's still some side quest style work: e-brake cables, pinion angle, brake line hook ups.
best case he's got big bolt pattern up front that he upgraded to when everything got done. if it's still small bolt, then either that needs to get upgraded to big bolt or hunt down a small bolt rear ($$) or do a 9" up with custom axles ($$).
and gawd forbid the fronts are still drum! that money on a rebuild is a wash. ain't nobody buying no 340/5spd car in small bolt drums for that kind of cash!
you're spot on with the assessment of the build. you gotta choose one lane or the other, building it for yourself there is a different approach vs a flip. if you're building it just to build it and the idea is to enjoy it and maybe down the line to flip it, the chances of making money are still slim to none. but on a flip, you have to build with the specific intention of flipping it and that means a lot of the decisions, directions and overall choices are specifically geared toward that end.