Dropped I-beam: how do I know if it's usable?

So, I've been collecting parts for my cadillac-powered model A for about 7 months and one of the last things I need before I start mocking up is a dropped-axle. I was gonna just buy the whole speedway front-end in chrome, because I wanna do a late-50s/early-60s-styled build, but I found out someone I know is selling a couple vintage Dago (sp?) axles, one is drilled, the other is chrome - both started life as '32-36 axles with a 1-1/2" factory drop and were dropped an additional 2-1/2" - I think. I'm headed over there tonight to look at them and, presumeably, buy one for my project. I don't have a spring, kingpins, shock mounts, or spring perches yet, but I do have a set of '40 Ford spindles and brakes and a set of Buick drums. My questions is - how do I know if the axle's usable? I presume it shouldn't be visibly bent, but there's a pretty big difference between visibly bent and correct. Also, how much slop should there be in the kingpin holes? I know you can sleeve em, but I figured the condition of the holes should play a role in value. I own a micrometer and know how to use it. Any other tips?
Thanks

 

Kingpin holes can just be measured and/or eyeballed for roundness...good bargaining point.
Easiest check is 4 rods stuck into the 4 holes so you can sight along them for straightness, easiy eyeball or measure angles. Everything is fixable, but a visual problem shown by a row of rods is a GREAT bargaining point again. Minor tuning will be done by bending axle ends to correct caster and camber.