The original power assist assembly is a complete bolt-on swap. Most of the repro parts suppliers offer replacement power steering pump, pulley, reservoir, cap, belt, hoses, hose mounting bracket and rubber, large bolt that holds the cast-iron pump bracket to the timing cover and power steering idler-arm and bushing kit. You may need to get original power steering pump brackets, control valve assembly, ram cylinder, the add-on crankshaft damper, idler arm bracket and the main steering tie rod. It is also best to use the original power steering sector arm since it is deeper than the standard steering sector arm. I believe you can also re-use your original tie-rod end assemblies.
The repro suppliers also sell the power steering fluid filters, but I buy mine in bulk from a filter supplier much cheaper.
You can have an almost completely new power steering setup from the repro parts suppliers, but the cost will add up to $$$.
You keep your original steering gearbox as it is