hi peter!
the f-150 and f-165 while similar, are not the same engine. the f-165 has larger induction components, different carb, different cam, higher valve lift (that's why the f-165 has the little bumps in the valve covers), shot peened cylinder bases and a nitrided crankshaft. it also, as you observed, runs at 2800rpm redline instead of the 2600rpm for the f-150.
while the franklin was a fine engine in it's day, the current lack of parts support from a factory or large aftermarket house (with deferrence to Susan Prall@A-1 Services) has IMHO relegated it to the sunday afternoon day-VFR status similar to rangers, warners, menascos, kinners, etc...
having flown behind an f-165 for over 12 years, my advice is to locate a nice 14-19-2 with as good an O-470 as you can afford. panel/paint/interior mods can be done as you go along, but the engine is the most expensive and critical item in a SEL aircraft. (although, come to think of it, some of those new avionics prices can add up to almost what an engine overhaul does :shock: )
hope this helps!
blue skies,
vic & N522A