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

Don't put yourself down cause you are young ,there are 50 + year olds on YT that don't know what they are doing with cars and display it daily for clicks LOL!
Cheapest thing to do is a 318 even if you re-ring and bearing and gasket the engine...(what used to be called an "overhaul")then sell the car "as is" no warranty its a classic car that's the game with that. Tell the new owner they can have "the original engine but it needs rebuilt" finish the flip and move on...the 340 is worth more sold separately without the car. This is just basic "business" ...