Been running my stock late 235 daily for 11-1/2 years now and about 90K miles, mostly under 3000rpm.
I got it when it was already 10 years past the last rebuilt, so probably 150K and over 20 years daily on the road.
I just replaced the head. Oil pressure is to spec and compression is very high and even and it doesn't burn oil.
I'm having a late 261 built for me right now.
Mostly stock, but with 254 cam (very mild) and electronic ignition.
Building for performance gives very little gains under 3500 rpm. The later 235/261 engines run practically forever if you keep it mostly under 3000 rpm with regular oil and filter changes.
