1966 273 Question

No such thing as a numbers matching motor pre-68, just period correct. Take it apart, have it tanked, bead blasted and measured up. You'll know real quick whether it's worth spending any more time on. Running but tires 318's are a-dime-a-dozen so junk it if it needs sleeves. Unless I was trying to do a 100% correct resto, I'd replace a worn out 273 with a 318 any day. The only outward difference is the number stamped in the front of the block.