Obviously, you can work out comp ratio any time you like, providing you measure the combustion chamber volume.One reason for doing the above is that there have been lots of different spec' Mugellos over the years, with different porting and different heads/comp ratios, and some suppliers even supply them with their own machined heads. An early head on a late barrel, or t'other way, can cause issue.
Starting point for jetting should probably be the common AV266, X7 needle (T2 clip position [2nd down from top), 122 main jet, 40 slide, 50 pilot... but this must be subject to testing (choke tests will give instant feedback) and adjustment. Do note that, just as with the threads currently running on iron vs alloy kits, a Mugello will be TOO forgiving if you get the jetting and/or timing (16 - 17 static as a starting point with high comp head) wrong as it'll keep running until it burns a hole in the piston, whereas an iron barrel will give you a big warning sign (nip up) well before it self destructs! Mugellos are so forgiving that they'll run until they pop!
However, get a Muggy set up well and it'll give excellent service, both in respect to performance and reliability.
Best of luck,
Adam
PS - Do take note of Cambridge's gearing recommendations as later Muggys like to rev and will not perform too well if you try to gear it for low rev work.
PPS - I like to run 28s on AV264 and X13 combo... BUT... start rich and work from there, hence the AV266 and X7 suggestion. Some Muggys may run AV268 X7 if using auto advance retard. All jetting will also be influenced greatly by pipe choice (don't remember reading this). A standard AF/KBM (or whatever they are) will cut the revs short of where later Muggys want to work efficiently, which is why the Ancillotti clubman revs higher.
