would it be possible to change the lower control arms and leave the rest of the stock suspension in there? or would you have to change the uppers and lowers due to measurements or component matching?
Also if i did get the GW or similar brand tubular control arms would there be anything else that would need to be changed? ie: shocks springs etc..
thanks!

I have the GW tall spindels and uppers w/ stock lowers.

The tall spindels use a special lower ball joint to fit in place of the stock unit (part that fits in the lower arm is same size as stock but the post that goes into the spindel is the same size as a B-body ball joint). The tube lowers might be designed to use a stock B-body lower ball joint instead of the adapter ball joint.

check with GW to be sure.

I assume you have cracked your lowers. You might do a search and find someone who switched to tube lowers and make them an offer on their old stock ones.

Your special lower BJ is a stock B-car / F-car etc (Moog K 6145) that has the press in portion turned down so it can be pushed in the smaller hole in the early A-car.

GW's lowers are stock geometry replacements. You can get them in either standard spring or coilover configurations, and with balljoints for either stock spindles or for tall (b-body) spindles.