It has been for a few decades now. I rescued the car from a local scrapyard in 1980. I originally installed a V8 & automatic but soon saw the light and installed a '54 235 & stick shift, then swapped in the 261. The car has a 3.08:1 geared 12 bolt rear and Mustang II ifs with GM brake rotors & calipers adapted. We have driven it thousands of miles, including several tips of 500+ miles. Our son & daughter grew up riding in it, being born in 1984 & 1988, so it will remain in the family, probably going to a grandson.
I plan to, probably tomorrow, remove the head and take it to be checked and resurfaced if needed.