Hi lazywork,
Yeah, I actually have the old weapon sets too! I bought them when I saw they were super cheap online.
The arm and leg armor fit perfectly.
HOWEVER the backpack is too tight. When I put the two pieces on I really had to push them in, and then as soon as I did I realized that probably cracked the circle joints. Those are the only rings that have cracked so far.
Afterwards, I used a hobby knife and shaved everything down so that it's not too tight. I'll definitely do that before I put the packs on for the other figures.
I'll take more pictures later today if I can!