Borescope pictures....how many miles on this engine?

[ErrorMargin]

I bought my 84 Targa a few years ago, the seller did not know anything about what had been done to the car. The car has 164k miles on the ODO.

The engine is very strong, starts right up every time, no smoke and had excellent results on a leak down test.

I do see some signs that the engine has been apart, studs have been replaced, etc. Also, the DME chip had been replaced with one that had a much higher RPM. I never found out how much higher, but I did note that it would rev past the factory redline (Which I avoided doing once I saw that it would do that).

I took a few pictures of the cylinders yesterday, see below.

Other than the carbon buildup, the cylinders look good and very fresh to me, but I don't know much about these things.

Is this good? Was it recently rebuilt?

Up until about 100 miles ago, the O2 sensor was disconnected and I believe it was running rich, which I suspect caused the carbon buildup.

All the cylinders look the same as this one.

The first picture shows the cross hatching on the cylinder wall with the carbon coated piston at the bottom.

The second picture shows where the cylinder head meets the cylinder. A part of one of the valves is visible on the lower left.

The third picture shows the piston, I tried to adjust it to better show the carbon.

[E Sully]

Generally I would say it looks to be in decent shape. The horizontal lines on the cylinder wall would give me mild concern but it doesn't look too be too bad. It may let a bit of oil by.
My 86' engine with less mileage looked a lot worse as far as carbon buildup. It was obvious the valve guides were quite worn.
I don't know exactly what was done to mine prior to me buying it, but it seemed it was run without an O2 sensor and had some funky aftermarket thing wired into the harness. It was made by Mike Valentine from the radar detector company, but he would not give me any information on it for legal reasons.
I did a top end rebuild on it, the Nikasil cylinders still showed good crosshatch and no scratches at an estimated 85,000 miles.
I put the wiring back to original and installed an O2 sensor. Afterward it ran like new. If your interested in what chip it has, you could take out the DME and see what chip is installed.