Turning my attention to getting the timing advance sorted as I think this could be part of the reason for poor running as well as carb tuning.
Going to invest in timing gun....yikes!
If it's a pre-80 A-Series then chances are there will be a 'window' on the clutch cover that allows you to see the timing marks on the flywheel. With an 'old school' points type distributor this can be used to set up the ignition timing more accurately than a strobe.
Can you give more details for the engine spec (cam, compression ratio, head, exhaust etc) and the type of SU carb you're using? Chances are someone on the forum may already be running fairly similar, and this should get you in the right ball park.
