Originally Posted by utopia

That doesn't sound stupid at all, though I would add that you might be best to at least get a sound runner in original condition rather than a full project with its attendant hidden problems.
You'll probably end up working on the bike quite a lot anyway, as they are addictively mod.able, so better to spend time doing that.
The good news is that the 2-valve engines are actually delightfully easy to work on, with the possible exception of the desmo valve clearances.
You should find one at this time of the year.

Early carbed motors had different cases, an internal clutch slave cylinder and a single phase alternator.
Later carbies had external clutch slaves (easier to upgrade to reduce the heavy lever action) and three phase alternators.
The differences are most visible from the lefthand side of the cases.
Of the two, I'd pick a later one, but its not a huge issue.

A carby monster is actually a great budget bike, if you service it yourself. ....apart from the expensive modding, that is.