Large Ball joints on a 72

My 72 Duster is a small bolt pattern drum brake setup in the front. Someone gave me the large ball joint A arms and new Moog balljoints as part of a conversion kit to discs.
My question is if I change to the larger A arms and larger ball joints can I stiil use the remainder of the setup that is there without doing the complete conversion at this time? My uppers need changed and I dont have the cash to purchase the rest of the parts needed for the disc setup and I hate to buy the drum ball joints knowing I will change at a later time. Will my current drum spindles work or am I facing a fit problem?