My 4l60 is bad right now. My first initial problem was that at wot in 2nd it would bouce off the limiter and in 3rd it would do it more severely. Now if i punch it 50% to wot i can feel the gears and every movement in the trans grinding bad...cruising it is fine but it still shifts later. i was curious to find out if it could be the converter rather than the complete trans. also, is my 87 trans am auto compatible with my 99 camaro ss, if so to what extent.

 

Just sounds like the trans is dying ,
As fr the 87 trans its a 700r4 not a 4l60e and while it can be swapped takes some considerable mods for tv cable, lockup , and other things and you would loose all tun ability also.
You would be best to get a 60e built for your car than attempting a 700r4 swap.