Want to bypass air pump

I'm trying to bypass my air pump on my 88 chevy 4x4. It's got a 350, power steering, and no air conditioning. The problem is I cannot find the right size belt. The belt needs to be 70-71 inches long and 4 rib. If I try buying a belt for and engine that didn't come with an air pump, the pulleys are placed a little different and its an 80 inch belt. I had another 88 2wd with the same setup, but I haven't a clue where the belt came from, so I know this has been done before. I've tried every part store and on the net, can anyone help me?

just take the belt into the store they will measure it up and they will find you one. don't tell them what it is off of.

Already tried, no one makes the right size, even though I know somone makes it. Anyone?