glad to see that you treat you baby gently! looks like I have the same issue as you, rear suspension too soft, so on big bumps under power the front floats over and the back bottoms out, which kicks the nose down. I may have a go at knocking up some new spacers to save having to buy new springs or adjustable shocks.
I have a spare used roll cage if you need any parts. I've just not got around to listing the bits on fleabay. PM me if you need it (it will cost you though, I ain't a charity!).
nip over to screwfix or BnQ, and get a mini pipe bender (for 8 & 10mm pipe in the plumbing section). Alloy cage is on my to-do list as well.