There's no guarantees, but if you build up a Tonti frame with good parts- it should easily run thousands of miles every month without problems. You will have to do some maintenance, though. Guzzi definitely has had issues with relays, connectors, the odd cast part and some poor choices of bearing retainers, but I think that it's Pete Roper who characterized most of the problems with Guzzi as the bean counters. 99% of the problems I've encountered on my bikes are operator stupidity. The base machine is brick-shithouse solid. Build up a good looking Guzzi, use good parts in it and it'll run like stink and last twice as long. The 5 speed has been around for-freakin'-ever. The clutch is bulletproof- use a RAM clutch if you like a lighter feel, but I'd advise against used Scura clutches.
Anthro- that is one ugly bike. Whoever designed it had a hangover, or worse.