66 C10 ball joints

[SS317]

I've read so many brake upgrade threads that my head is spinning.
Truck is 66 C10, Drum, Drum, stock front end.

I am taking my truck in Friday morning to get an alignment. It's been pulling to the right and I don't want to wear the new tires the wrong way. I'm planning on upgrading to front disc brakes eventually but budget does not allow it right now. Question is, if I have to replace the upper and lower ball joints, will the 73-86 ball joints fit the stock spindles? I know I have to upgrade the spindles to do my disc upgrade but that could be a year or so down the road and I need to drive my truck.

Thanks.