My El Camino when 300,000 miles on the original 305. It was starting to smoke a bit and stunk up the garage when leaving. When I disassembled it just to see how worn it was it looked pretty good. The valve guides were worn and the valve seals were like rocks.
The cam was fine. Just doing any machine work on a 305 was more expensive the just buying a brand new 350 that just dropped right in, and the water pump, starter, alternator and AC compressor all just swapped over. $1,700 for the brand new 350 was just too good of a deal. And it came with a 2 year 24,000 mile warranty. It has 90,000 miles on that engine.
