Do you have a good ground wire from battery to the engine and frame?
Connect a booster cable from battery neg to engine and from battery neg to frame and try starting it to see if it’s better.
There’s also an ecu ground wire at the back of the head just above the bellhousing,if it’s broken...
check the short fuel pickup pipe on top of the tank,ive seen so many of them rusted with pin holes there....
try running engine from a jerry can from the primer pump
jusr read the whole thread,very impressive rebuild with minimum tools,i know its hard to buy tools in asia when i was growing up,l grew up in the town Limband,next to brunei,i was just there oct,2022,visited kuala lumpur,kuching,limbang,koto kinabalu.
also what a rare find,a 60 series in good...