1969 merc 800 low compression

Need input about low compression readings.friend asked me to fix his merc 800 from 1969.looking at it:wiring needs replacement same as fuel lines.now i did compression test for him and found #1 175psi,#2 175 psi,#3 30 psi, #4 170 psi.power head was rebuild by PO.now,when i sprayed oil in low comp. cyl.it jumped to 60psi.could this be symptom of stuck ring or its more severe damage.i didint pull transfer ports yet.motor run fine last time it was in water.is there anything else i should try to bring compression to par??

Pull transfer cover to inspect.--------This does not sound good for the wallet.

Update,i took transfer port covers off to inspect low compression piston/rings,"hoping" to see scorched and scratched cylinder and pistons.to my surprise inside looked clean.top and bottom rings had springing motion.middle ring seemed little tight.so i sprayed sea foam and worked a piston for a bit.after putting cover back,nex step was to check compression again.it occasionally jumped from 60 psi to 90 psi.after more sea foam treatment it settled at 96psi.was not enough,so water jacket came off.nothing indicated cracked cylinder head.i even took readings while jacket cover was off,looking for oil intrusion.nada.ok now occasionally psi jumps from 96 to 120.is it a good thing.maybe there is carbon build up on exhaust side??any input is appritiated.
#2...i have no voltage on white wire on switch box.does that indicate bad ignition switch.i am getting spark when white wire is jumped to red on switch box.can I install toggle switch by control to jumper those wires to run the engine??