It's hard to find an engine that's more reliable than the Chevy inline six cylinder. About 1976 or 77, I picked up a '64 Nova with a 194 in it, and the motor had a knock in it. I figured that I'd drive it until something blew or broke, then rebuild the engine or get one from a junk yard. I drove the car from when I bought it until 1981 with that knock in the engine, and it kept on running. I finally put an oil pressure gauge in it, and the oil pressure was always fine. I never did figure out what the knock was, but it never seemed to bother anything, and the engine was still running fine when I junked the car after a lady friend borrowed it and got rear ended in it.
