I'm doing this poly suspension upgrade and all the boots to the ball joints are torn in 2 but looking at the ball joint it still has plenty of grease and looks good wear wise. Should I replace the ball joint regardless or can I clean it up, regrease it and just install the new poly boot? I don't know of any good way to test the joint. Maybe it would be best just to get rid of it and put in new ball joints regardless? All my tie rod ends look the same way as well.

 

I say replace them if the boots are torn. Some will tell you to replace the entire control arm assembly (this is what the factory service manual recommends), but I replaced mine and have not had any trouble with them.

https://www.rx7club.com/1st-generation-specific-1979-1985-18/replacing-ball-joints-502398/

Rich