Sounds like it is time to build up our own spring pack.

As a 73, you have dumped all the iso clamp crap?

To build a pack, choose the main leaf you want to run. Align your second leaf so the tip of its front edge is directly under the spring eye of the main leaf. Drill the new mounting hole to match the housing alignment bolt. Align the balance of the pack to similar spacing as it was before as you redrill each leaf to its new position. Add or subtract leafs until you reach a rate you're comfortable with.

If you want to copy the Hotchkis principle, you can cut a single leaf to be square on each end and mount on the top of the main leaf to run from the spring eye area to the axle housing pad.