Some info here
http://www.stovebolt.com/techtips/wheels/

Yes Chevy had 10 lugs on the 1.5 ton trucks in 56-59 and on the 2 tons they had 6 lug Budd in those years, then dropped the 10 lugs in later years.

Yes there are 22.5" wheels with 10 lug on 7.25" diameter bolt circle out there, they are not all that common though.
I've got a set on my truck and have seen a number of others, you've just got to keep looking.

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
---All pictures---
"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-