I'm new to bus conversion. I am handy and want to do my own conversion. I don't want a large 40 footer as it is just two if us traveling.
I found a 1990 diamond coach made by Coons of Oswege Kansas with 16,000 miles
Any thoughts or recommendations
From the looks of it, you are looking for something smaller than the 35 foot and up size range of the intercity "Greyhound-like" coach. You seem to be looking at newer buses built for school and shuttle-bus use. A better forum for this is <www.schoolie.net
That said, many of the buses in this class have front engine snouts which cost you 20% or more of useable square footage and make the bus that much less maneuverable for a given length.
This all assumes that doing it yourself from scratch is more important to you than either cost or getting on the road. By the time you finish you will have spent as much or more than purchasing a completed unit. The appearance of savings is that costs are spread out over time. Some participants on this board have spent over a decade saving money and still don't have an operable conversion. Many others say your first conversion is just a trial run.
I second Lovrbus's advice. That way you get a useful setup and with your skills can tweak, modify and upgrade with experience as your guide.