I have just completed an extensive top overhual on my F-150. The engine was acquired from another aircraft with only 540 hours since overhual, however that overhual was in 1963! Obviously I wanted to replace all gaskets and wanted to get a look at the crank journals before investing any effort or cash in the engine. I also had no information on whether an oil filter had been installed which was fairly unlikely in those days. I consider the oil filter to be even more important to engine life than the use of modern lubrication oils. So the net result was that for $2700 in parts and cylinder labor, I got an engine with new cylinder liners, a valve job, new rings and rod bearings, all new gaskets, and all top end parts within the clearances allowed for a new engine. This is a small price to pay to eliminate most of the unknowns of an engine before it is installed in the aircraft.