shocks and springs for offroad

Hi,

I've bought a W460 230G cabrio (1980) that I'm slowly rebuilding to be used on trophy competitions, won't be used on-road. The engine will be a 300GD.

Right now I would like to replace the original 2 stripe yellow springs and the stock shocks. I'm trying to decide between the trail master +40mm and the front red / back white combo. Is the 40mm lift really within the acceptable limits? I've heard conflicting opinions. I don't want to weaken or rebuild things too much.

For the shocks I've read everywhere that the Koni HT Raid seems like a good choice but it's quite expensive. Do you have any experience with Bilstein B6 or B8? Or these are available in offroad version too, what about those?

Right now I'm running 31x10.5x15 simex pattern tyres but planning to upgrade to 33 or 35.

Thanks