[Dingfodgy]

I don't think you can put '73-'87 ball joints in '67 A-Arms. But then again I could be completely wrong. The easiest way would be to either use the donor arms and spindles and then change out the tie-rod ends to the '73 style, or bolt in the entire x-member and the whole shootin-match in one fell swoop!
As far as lowering goes- there are many methods. Some I would recommend and some that would qualify you as bona-fide trailer trash! The first question is "how much drop"?

Best Method: Dynamic Drop with tubular trailing arms or dropped spindles with Shockwave air springs. (i.e. ADJUSTABLE!)

Better Method: Static drop with same arms or spindles w/ stock or lowered springs depending of how much you're lookin for. (i.e. NON-ADJUSTABLE!)

Good Method: Static Drop with lowered springs + blocks, depending on how far you wanna go.

Bad Method- Cut out coils in springs or heat and collapse coils. (i.e. Harsh ride and totally jankity)