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

OK I'll try some positivity on this thread, as my perceived reality was taken as negativity.
How quick do you wanna make $$?? I would say with the majority of muscle cars flipped, that the majority of the "better" profits are made when the LEAST amount of work is done to them.
Diagnose WHY the 273 won't run. It may be something relatively cheap to do.
While engine is out clean tidy engine bay.
Then elbow grease to the entire car. Doors/windows operate. 67 is 1yr only windshield gasket/trim, same with rear. It's a notch right? Well to convert over to the MUCH better 68 and up stainless ws trim requires finding ss trim(good luck $$$), removing glass, installing new clips and new gasket. Right there the trim gasket and clips would probably put u close to $800. Can u remove glass on your own? If not, add another $200 or so.
Most people on here can do their own normal maintenance, brakes etc.
Make it running(not necessarily driving) and presentable.
There are A LOT of members who have helped me and vice versa in the "parts department", trades, great prices etc. Most of that comes from respect and willing to help each other knowing it's going towards a members car that he/she is planning on keeping. If someone comes on here looking for deals(remember these are Mopars, so ANYTHING aftermarket as well as oem is limited), and prospective sellers know ahead of time the car is going to be modded, flipped by a 1st timer, do you think "pricing" may be different?
Get engine running, if ya gotta swap engine go for another small block and try to get 69 and earlier as pumps/pulleys will interchange.
I'm not an expert here but my Mopar focus/experience has been with 67-9 cudas for over 30 years.
Good luck.