Very unusual bus you have there. The sloping windows are not anything I have ever seen on a "skoolie" so I'm guessing a transit. You might find someone familiar with it on skoolie.net as some of those folks have seen a lot more buses than I have.
And I have to agree with MikeB...transplanting onto a newer chassis could be a life-long project for many reasons. Fix what you got and roll on down the road.
