Re: new to buses "need opinion"
If you're looking for a simple project, this might be too much. It depends on what you're looking for and what you're willing to spend. If you really want an old bus, have the $$$, and the knowledge (or willingness to learn) this might be a good project. My guess would be that depending on the chassis you shouldn't have too much trouble finding parts. There seem to be a lot of Bluebirds on Chevy and GMC chassis during those years and it seems that they pretty much never changed the gauge package on those.
The other side of the coin is that there are plenty of good running buses without the mechanical issues you describe...just maybe not that old. As with anything, it's really up to you to decide what you want to tackle. Best of luck!