The only problem I have with my SU's is when a float sticks, the bowl overfills, and it dumps gas on the ground.
Sounds like your needles need to be centered and pistons adjusted. If you have a SU tool kit it makes it pretty easy. I have not done that for such a long time.
Thanks! I need to hit my MG book again! The twin cam was very cool only saw one once, never saw a coupe.
With all the motorheads I may have put together a team when I rebuild my 74 Bronco that has 302 in it.