three SU's carbs would look good on there, that's what MG's probably had. My old volvo has them too , very reliable things.
something handy is a plate with 3 - one inch holes and 3 - 1/4 inch holes.. that can be mounted over all 3 carbs with air cleaners removed. .
the 1'4" hole is for clear plastic tubing , what that does is allows you to synchronize all 3 while they "breathe" through the 1" hole. then you can run each clear plastic tube upward, then down to to a can of water and watch the height , which relates to the vacuum draw upon each carb.
the reasoning is to get equal draw and throttle response form each carb. as the throttles open up you should see the water rise in each hose equally indicating the same vacuum for each.
that way you have a reference for synchronizing..
th ereason I mention is is while you are milling out an adapter plate . a plate to synchronize them is perhaps handy later..
if you used something different from SU's there is still probably some synchronization,,
SUus would look "kind of right" on an MG. some have larger jets.
It seems like a lot of weight for an MG but I hope you win anyway, sounds fun.