oh no, is this 8.75 housing too bad?

So someone please help me straighten out my brake situation. I got the rear end fixed, new housing ends on it, and it was all put centered on the jig, which is all good. Everything is in the car, and now I went to put the brake hardware on and everything is all wrong. I thought I had 1 3/4 size brakes, because I measured the friction surface on the drum, and it comes out to 2.25". All of the 10" x 2.5" brake drum measurements show that surface as much larger. So I assumed, which you know what that means, and I bought the 1 3/4" shoes. When I got everything on there it just didn't seem to fit quite right, and I did some checking and I guess you can measure the backing plate from the flat mounting surface to the pads where the shoes ride, and if it is the 2.5" that would be something over an inch or so, and if it were the normal a-body 1 3/4", it would be more like 15/32 or something like that. Well mine is clearly at least an inch, so now I'm thinking I have the backing plates for the 2.5" shoes? Anyhow, the problem then is that he gave me the drums that have the 2.25" friction surface. They have a bell type outer rim. So what did he give me? Did he give me a drum for 1 3/4" shoes and the backing plates for 2.5" shoes? I was supposed to be on the road Saturday. This is killing me. If anyone has any info that would help me determine one way or another what I need to do, it would be helpful. If I need to buy 2.5" drums, then I can do that, if I'm sure that's what I need (and new 2.5" shoes). Or is the information about the measuring of the backing plate wrong and I'm worried about nothing? -edit - Forgot to mention the axles measured 27 11/16 from tip to outside of flange, so the axles should be the proper length to match with the 10X1 3/4 backing plates right? So if I have 10X2.5" backing plates on there now, with the a-body length axles, will that be a problem if I try to match them with 2.5" shoes and drums? I believe that would be a problem, and if that's what he sold me as a working package, he was wrong, and I'm screwed. So I think I would have to then go and find the proper 1 3/4" backing plates, or get new axles, neither of which is going to happen in any quick amount of time. Can anyone confirm a definite way for me to tell one plate size from the other?