I run Triple 45mm Dellortos with 36mm (correction 34mm) chokes. I calculated this with the help of a friend, he was going to sell me his 45mm webers and then backed out and then said yes again. By this time i was saying i'll go get my own. I started off with 40's on an almost stock motor then after i put a part of one of the rings out the bore i did it rebuild. It now has,
2mm shaved, ported and cc'd N42 Head
Stainless valves, arp stud kit, crow cam and springs
Adjustable cam gear, Electronic ignition, genie headers
Blah, blah blah blah (i could just keep going but you get the idea)
I get over 400 kays per tank on highway and on average around 300 city milage with a modified auto. Now what was my point....... a yes the 40MM Dellortos were fine i just wanted 45's out of spite and then bulit the rest of the motor to suit. Once you start modifying it's a full package that will get a good result, bolt on are fine but it depends on what you want and how far you'll go with it.
Oh and i'm very pleased with the output of my engine, can't wait to get it on the Dyno.