You are sure the timing is correct and the balance shaft is in time? Engine turns free and nothing touching in the crankcase? If all ok, have you checked the timing key between the flywheel and the crankshaft.
Compression is on the low side, did you check the valve lash on the engine when you had the head off?
Yes, clearance is lash. Valves may not be seating. Easy enough to check, by removing the vent cover.
There is an adapter for the starter pawl, but usually hammer and punch is used to tighten the nut.
clearance is checked between the valve stem end, ad the tappet, with the valves fully closed. Adjustment is done by removing the valve and grinding of the end of the stem in very small amounts. .006 is perfect. But as long as you have something close, it will work. But zero will not work, or if there is a large gap, the valves is likely not seating in the block.
Will leak oil, but it won't keep engine from running.
Timing has to be correct, crankshaft and camshaft marks. and the flywheel key; Then it has to have spark , compression , and fuel and air to run. Do you have spark? Will it run for a few seconds, if you put a teaspoon of fuel direct into the cylinder?
I remove the spark plug and put it direct into the spark plug hole, re-install the spark plug and try it.
Spark ok, no run at all. And you say compression was 60 psi? valves ok, was flywheel tight before the first attempt? If not the flywheel key can be sheared.
If you have spark, it is not a safety switch problem.
Low compression or the timing is off.
!! Timing key for flywheel has to be perfect. Not any damage!