[Tim Hancock]

Richard, a Cherokee or a Cessna 172 will end up being boring if you fly a lot in your first few years, but if you only fly maybe 25 hours a year, they will be fine for a few years as a new pilot. If you make the mistake of attending Oshkosh however, I am afraid you will find yourself looking at various other types.

Lycoming 150 hp (O-320) engines can get the auto gas STC, Lycoming 160 hp (same basic engine as the 150 hp but with higher compression ratio) and Lycoming 180 or 200 hp (O-360) engines cannot run auto gas due to the the higher compression ratios. Older 172s often have the Continental 145 hp six cylinders whereas some of the slightly newer ones use the Lycoming. I am pretty sure most of the lower compression Continentals can also use the auto fuel STC.

As Joe stated, engine TBO times are just guidelines. An engine that has been run often, typically has a better chance of getting close to TBO time whereas an engine that took 25 years to reach TBO, may not have as good of a chance. My advice would be to buy an airplane with 1000 hours or less since the last engine overhaul. If you have to overhaul the engine while you own it, you will NEVER get the money back out of it.
It has to be done by a liscensed mechanic or overhaul facility and it will end up costing you in the neighborhood of $15,000+ by the time you are done. A $40,000 172 will not be worth $55,000+ a few years later even with a feshly overhauled engine.

A pre purchase inspection by a GOOD mechanic is pretty important unless resale value is not important to you.

Good luck. PM me if you want to discuss further by phone.