I have a '71, 22' length, torsion axles, and Dexter 4 bolt rims. It rides on Carlisle 15" RH Trail Load D. It rides like an extension of the truck, even without a WDH. I topped out around 6K lbs. With that dual-beam suspension, make sure your frame is really good. If adding lumber, weight goes up fast.
I'd pretty much suggest, like others, to start saving for new axles. BTW, also suggest to wire your brakes in a "star" scheme instead of the typical "daisy chain". For the extra $10 in wire, it is a big improvement and, if you lead all your brake wires to a terminal strip, it makes diagnosis of any trouble, much easier.
If Etrailer doesn't sell the lug bolts, a fastener distributor can get them for you.
