It does not sound like a carb problem to me either. I have probably read at
least a dozen ways to set the timing on our British cars, one which is easy
and at least gets you started is to slacken the distributor locking nut and
turn the motor on, then with gloved hand turn the distributor back and forth
by hand slowly until you get maxium revs. This will not be absolutely
correct timing, but should get you in the ballpark so that if all else is OK
it should idle OK.
Then you can use the timing light, or back off advance until it doesn't pink
under load to fine tune timing.
Also make sure your plug wires are all going to the right place.