Kim:
I built a belt sander years ago. I made it so I could run, I think, three different belt lengths all 2" wide. Also made it to mount on the wall. It works well but I haven't used more than one length belt. I looked around the Internet and picked some of, what I though, were the best DIY ideas.
(https://lister-engine.com/coppermine/albums/userpics/10011/belt-sander-1.jpg)
I don't remember where I "borrowed" the table tilting from but I found it slick. Each hole is set for a different table tilt. Pretty handy for touching up HSS lathe tools. May or may not be worthwhile for your belt sander build. Here are two pics.
(https://lister-engine.com/coppermine/albums/userpics/10011/normal_belt-sander-2.jpg)
(https://lister-engine.com/coppermine/albums/userpics/10011/normal_belt-sander-3.jpg)
I think I have an overall *.dxf drawing to scale (you can view individual parts on layers). If you want a copy of that file let me know and I'll shoot you a copy.
But that does look like a nice unit, easy build. I think you should go for it.
Thanks.