Ford's 300 was developed from a 240. The only difference was the stroke. IIRC, all the parts were interchangeable except the rods. The 240 was as reliable as the 300 would be but just had a little less torque. Once the 300 came out, the 240 disappeared quickly. I had a '68 F100 with a 240 and it was highly reliable. I didn't do a thing with it in 100k miles. If it had been a 4x4, I would have swapped the engine for a 300 and would still be driving it.
