Is it possible the needle/ seat/ float has stuck? I've had problems with that. Part of that may be due to the float / pivot which is sort of "riveted" to the cork float. They get loose and may bind in the bowl. Pulling the drain tells you if it's empty. If it has fuel there and won't run, there's gum in the orifices. Sometimes you can get them going by simply squirting some aerosol cleaner into the needle jet area (remove the idle needle as well as the bottom plug/ needle) and blow a little air gently through.
I NEVER hook up electrics to test them. If you need to crank it, just "rig" a scrap battery wire/ jumpers to the starter and a battery.
Main issues: Bad coils (epoxy cracks if coils are not recent) bad points and condensers. Bad water pump and water leaks into gearbox. If you pull the carb to clean it, take a light and look at angles into mainifold at reed plate, looking for signs of corrosion.
I have some of those from 55/ newer and if there's been no water intrusion into the carb/ block/ cylinders, and if they aren't worn out, they will run. Only other issue (not a big one) might be air leaks in through the upper / lower crank seals.
