Motor won’t stay running
( I haven’t timed it yet. )
Well that's probably it then, not because the timing is wrong but because with too much timing, the throttle has to be closed to not have a high idle, and when you close the throttle, that shuts off or at least reduces the amount of Transfer-slot fuel dispensation.
My guess is that an extra turn of the curb-idle screw will get you in the ball-park. If the idle speed is too high, just retard the timing until she is happy.
If you take the carb off, reset the transfer slot exposure to between dead square and a lil taller than wide..... then leave it there! adjust Idle-speed with timing.