My thoughts, the best Weber for a street 1275 would be twin SU's. I don't have anything against Webers, but the originial SUs will perform as well as any Weber until you get into a full race engine and then many racers still run modified SUs as rules require. The main difference would be felt in off idle throttle response between SUs and a DCOE or DGV, as the Webers have the ability to go to a fully open throttle bore immediately and use an accelerator pump to compensate for mixture leaness, where the SU opens on demand from the engine vacuum, a bit slower but no accelerator pump needed and you can't "bog" an SU because of this. But you said street engine and immediate off idle response isn't that critical on the street, so SUs would be my choice.
'73 Midget (V6)
'59 MGA (I6) under construction
'73 Lotus Europa
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