Lowering leaf springs

front and rear bars in a matched set - use rubber bushings on the rear bar - this allows for tuning of the suspension via how tight the bushings are held. It works very very well. I have lot's of experience making old cars handle [rotate in the turns] and stop.

Rubber suspension bushings including the lower control arm.

Adjustable strut rods with the rod end are best. Use of these allow you to square all 4 wheels to each other as well as making sure the suspension moves freely thru the travel and holds the wheel steady under duress.This requires a plumb bob, masking tape, a very accurate tape measure and a good assistant.
They will help to a degree with the caster.

Bilstiens are one size fits all, adjustable shocks are way better.

Too bad you can't weld/box the k frame because a welded up k frame vastly improves everything. Weld plates to the lower control arm.

Rear springs- do not do not use lowering blocks-those are for amateurs. You can have the right side extra leaves removed and the springs de-arched or buy some thing in the 130-140 range

Brakes - rear need 10 inch drums with semi metallic shoes