Im not entirely sure what you need but id be checking to see if its possible to run a handbrake cable through the floorpan to rear axle first, before proceeding with any conversion.
Parts wise, id say youll need calipers, caliper carriers, cables, maybe handbrake lever assembly, and discs. Plus rear flexy brake hoses and possibly load sensing valve.
Don't know alfa33 that well but might be easier just swapping over rear axles (with rear shocks probably) or if you can unbolt the stub axles from axle ends do that.
Hope this is of some help and not too technical for you, id be keen to know how to go about it, as I might convert my sud too.
I saw a sprint at a show with a conversion but that would've already had cables routed through floor to rear for drum brakes beforehand.