When I started accumulating stuff to rebuild our 67 Barracuda, I looked high and low for a 273 to replace the junkyard 318. After I looked at prices for a good one to rebuild, plus the cost of the rebuild, I started looking at 318 long blocks. I got real lucky.
An engine retailer on eBay was selling off a batch of 318 long blocks that had been rebuilt by AC/Delco. Not many of us bid - I got one for $600 delivered to a freight center about 25 miles from my house (in TX). I had it mothballed for several years, but I put Marvel Mystery oil in the cylinders and turned it over ever so often. No signs of corrosion inside - sounds great so far.
I would have liked to have a rebuilt 273, but I just couldn’t justify the cost.