It looks like it’s had some cosmetic stuff done to it. The difference will be in knowing what certain measurements were stock and what the engine you have measures. The grinding on the outside of the liner alone won’t do much if anything, however if the timings were changed and work done to the crankshaft... then you may really have something. Look at the top of the ports (towards the top of the liner). If you see brass across the whole port window top, it’s probably been modified. If you see chrome, then it’s not been changed. If you can degree the engine and take some basic measurements of the crank, I can give you a fair assessment of the engine.