Just the odds of so called numbers matching after 52+ years is wishful thinking, in reality these engines from the 1960's needed a full rebuild after about 80,000 miles. they just wore out. Guys were not thinking about the whole numbers matching thing when they bought them. My uncle bought a 1967 400 4 speed Firebird brand new and beat the crap out of it when he got it home. He had blown up the original engine and got a replacement. Those days you could go to the dealerships and just get another one. There's lots of cars out their claiming numbers matching. far from the truth.
