273 question
Did the shop measure anything? Typically, a 273 would have a forged crank which usually only needs polishing. Bore depends on wear, only bore it to what it would take to clean up the cylinders. Rods should be good to go, new cam, lifters, and valve springs, double roller timing chain, new oil pump with high pressure relief spring. Heads will probably need guides, 8 exhaust valves (get stainless steel ones), Viton valve seals, and a good valve job. Not sure how that would add up to $3,500 + parts. It is not a Chevy, I doubt all that work would be required to get a good rebuilt 2 barrel 273. A 318 should also be a bolt in, but would cost pretty much the same to rebuild. Maybe a 5.2 magnum, but those usually need the heads replaced, but not always.