I would also check the welds at the brackets for the lower A frame . I have seen some that were poorly welded from the factory. Since you are cleaning things up.
Update on frame with some pics. Got a local welder to come out to the house and weld some square patches on the frame where the crack was. The crack has been well covered/re-enforced by the patches. I also pulled the rear crossmember off as it was bent (more so than came stock) and had the welder put in a reprop one I got from OPGI. Once all that was done, put 2 coats of self-etching primer, 1 coat of regular primer, and 2 coats of flat black. I think it came out looking good. I measured the frame (using dimensions from the service manual) and it all lined up. I'm working on the front suspension/steering now, blasting stock control arms, gonna repaint them, putting on new proforged tall ball joints, replacing all the bushings. It's coming along slowly, but I can start to see it. Here's some pics of the frame.
@12lives Yup, just ordered some Proforged Tall Upper and Lower Ball Joints, I think the uppers were .9" and the lowers were .5". For the inside, I used the Eastwood product that has the hose attached to get in the enclosed parts of the frame. I was able to get in the "C'" channel part of the frame with the rattle can. I'm assuming/hoping that I got the enclosed part coated pretty good. Anyone got any tips/tricks for getting the upper control arm shaft out? Ball joint press kit wont seem to work, I've been posts on using a compressed air hammer chisel to get it out. What about when pressing them back in? Also, I got the rear axle housing bushing out, any recommendations on what to replace them with? Moog make some for the rear axle housing bushing?
For the rear axel housing bushings, I bought the Moog K5161 for my 69 GS400. I haven't had time to install them yet. There was another thread on here somewhere that covered this, and that is why I bought those.