(Newbe) 273 to a 340 and tremec 5speed swap.

Do you already own the 340 5-speed?
At 17, shouldn't you still be in school?

It's highly unlikely that you'll get your money out of this swap
IMO, that car is light enough that for a street car, it doesn't need a hotrod340, nor a 5speed.
It would be fine with a 318-4speed, and proper street gears
or a 360, 3+1 A833-overdrive, and any street gear.
But , I guess if the 340/5speed drops in your lap for cheap .......... I mean I would build a car around that combo......
but I'm 70, have the tools, the knowledge, and the skills, to make it work.
Good luck young George.