A few years ago, i had almost exactly the same decision to make. I was wanting webers on my L26 (unbored) with stage II cam. 40's or 45's??
All the guys in the USA chatroom (IZCC back then) strongly suggested 40mm, but the calculations with engine displacement and rpm, suggested i could get away with 45's (with smaller chokes). I was only 25 years old and bigger was better, so i went with 45's and regretted the decision.
It was great at full throttle, but under part throttle acceleration there was surging / hesitation. I took it back to dyno tuner twice and they couldn't completely get rid of it. The car drank like a fish and I had all of this un-driveability for just 94rwkw.
Webers ended up coming off. I will only ever put triples on a road car now if its going on a reasonably hot engine (compression, porting), otherwise your small gains will not be worth the headaches. But, if you have your heart on them, go for the 40's !!
My 2cents....