65 Barracuda... Got BAD News...

There's no reason to go to the time and expense of rebuilding your 273, just get the car running. My suggestion is to try and find a good running 318 (craigslist?) as it's a direct bolt-in, shouldn't be more than $250, maybe find someone parting out a car and you could check out the engine before it is pulled. Most of the work/cost would be removing original engine and installing the 318, I don't think it's easy work for a novice as these engines are a tight fit in these cars.

You could also sell some parts from your 273 such as valvetrain (since it is a solid lifter engine), the accessory drive pulleys and maybe other things to offset your expenses.