I have what is to me the holy grail of belt sanders, a Porter-Cable G8 wet/dry 5HP machine. I use 9 x 108 Norton belts, although there's enough width for a 10" belt. I've never tried using it wet. I believe the drive drum turns at 800 rpm and that it is approximately 10" in diameter. I never paid too much attention to details or sfpm because the beast always did what I wanted.
This sander will remove a fearsome amount of metal. I used it for beveling steel for welding, general shaping, etc. and never had a complaint. This is a pretty basic vertical belt sander. The table is fixed perpendicular to the platen, so grinding to anything approaching a precision angle is out, but then belt sanders are by definition not precision machines.
I had a Burr King 1 1/2HP sander at one time. I hated that thing. It ran blazingly fast with its 3500 rpm motor and scared the hell out of me. It's awfully light for any serious work but if you can get past the high speed and generally unsafe feel of the machine, it's okay for smaller work, I guess. I got rid of mine and never missed it.
The G8, by contrast, is very sedate and confidence-inspiring, while still hogging away a prodigious amount of metal. The problem will be finding one of the old things, since they haven't been built in ages. I believe Hammond made/makes similar heavy machines. I'd recommend calling around to various machinery dealers or checking plant liquidations. That's how I got mine, about 30 years ago. You may get lucky and find one too.
Steve