Both valves do NOT close on overlap. Furthermore; the Exhaust is CLOSING while the Intake is OPENING.
If in fact the piston is at TDC inside the cylinder, with your valves that far out, I doubt it would start. But if it did, it would take a lotta lotta throttle to keep it running.
Have you done a compression test yet?
Here is something you can try;
With the #1piston on the overlap cycle; rotate the crank to where both valves are similarly far opened, the exhaust closing while the intake is just opening. Put a straightedge across the spring retainers, and jockey the crank back and forth until the straightedge is touching the two retainers in a total of four places, thus putting them at the same height. Now you are doggone close to Split overlap.
Now go read your timing tape.
you should be seeing from 4* retarded to 8* advanced. Anything outside that range is not gonna run right, especially at Idle and at LOW-rpm.
Here's another clue;
If it idles at ~700 with the throttles in the normal relationship to the Transfer slot, then I highly doubt that you have a cam-timing issue.