Let me talk about a few things:
#1. I don't know about the different makes of axels.
#2. If you go to an above spring arrangement you will lose space above the tire. IOW's the tire may (or may not) rub on the wheel well. I would not do this but if you do make sure you check and recheck for clearance.
#3. You cross measure the axels. You measure on an X. You can measure with a tape or even a string. I doubt most trailers are within 1/16th of an inch. More than likely a U-tube vid on it?
Good luck and have fun!