Front end rebuild parts Interchangable ?

I'm not too experienced with early A-bodies. Mainly 70 - 76 A bodies, I've done a little with my buddies 68 Barracuda but that's about it. (67-69 Barracuda is possibly my next car if I can't find a decent 71-74 Satellite).
But I'll do my best, I believe that early A's have narrower k-members. Even with disk spindles from 73-76 you still have steering components from 65. Whether or not they play well with upper control arms from 73-76 is unknown to me, but it'll definitely alter your alignment base I believe but the 65 Dart pitman arm is different.
PST | Car & Truck Suspension Parts | Performance Suspension is also an awesome site to use if you're seriously thinking about modernizing you front suspension further. They have resources that may help further.
I've used that site to that basically converted my Duster into a handling machine using QA1, PST and Proforged parts.
Also note that 73-76 A-bodies have 2 different pitman arms. one for power steering and one for manual.
www.Rockauto.com has pitman arms for the 65 dart from Proforged. Proforged makes decent products.