Hi and welcome to the club!
Are you in the UK? 75 series are pretty uncommon in these parts and the PZ engine even more so! IIRC the 75 has leaf springs front and rear? You could try West Coast Overland who stock the Ironman kits, which is probably the cheapest you're going to find in the UK. I doubt they carry stock for your model though, so you might have to wait a while.
Alternatively you could find a spring manufacturer to make you new leaves - this could be a bit hit & miss though. I imagine you could find generic shocks to fit too. This would be the cheapest route I imagine but the end result might be a bit iffy. The benefit of the kits is that components are matched.
Good luck and let us know how you get on!
Cheers,