72' step side rear end

[hotrod9454]

have a 72' step side with a leaf spring rear end and am trying to lower it. I have installed new 3" lowering springs but that did not do it for me. I am considering changing the rear to coil springs. Is the rear end width the same for a fleet side and a step side? How hard with this conversion be?
Anybody got any better ideas? I'm getting tired of throwing my money at it and not getting the desired results.
Please help with any suggestions!

Thanks