In my limited experience, the F-head engine gave about 15000 to 20,000 good miles, followed by about 15,000 bad miles and then you replaced the engine. I was going to suggest a mechanical gauge, but I see you've already figured that out.
One of the weaknesses of the Jeep blocks is that there is only one replaceable bearing for the cam. The remainder of the cam supports are the block itself, which means any wear in that location will not be fixed by merely turning the crank, new bearings, and replacing the one cam bearing.
That said, oil pressure is highly overrated. I worked on one engine recently where the owner had the motor rebuilt, but could get no real oil pressure reading. They changed the sending unit, then changed the gauge, then changed the sending unit....
Anyway, going along on the highway, the engine suddenly seized up solid. When I tor it down, I found that the re-builder had neglected to put the front oil nozzle back in (sprays oil against the timing gears), thus leaving a 3/8 hole wide open on the main oil gallery. And yet, the engine had survived several years like that.
If it does come to a teardown, they are a great little engine to work on. I used to do them in my basement back in the old days. The problem was getting the finished product back up the stairs.
The fuel line does indeed run across the front of the engine, then up and across to the carb. My guess is it keeps the line away form the exhaust manifold. Personally, I have never had an issue with vapour lock on the Jeeps. Best place for the filter is down at the frame before the fuel pump.
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