You would need to recover any gas in it (any fridge mech with the right gear and the
correct qualification should be able to do that for you) before stripping the system and swapping the bits over. Replace all seals for new and make sure they are compatible with the new gases. You would then need a suitably qualified engineer to re-fill, test and certify the system.
TBH, with the current re-sale values of a 3.2 Fronty these days I wouldn't have thought it would be worth the effort unless you are intending on keeping the thing for a few years.
F Gas Guidance For Users - Further reading HEREF Gas Requirements for AC in Cars - Further reading HERE
This posting may have been helpfull, on the other hand probably not... Either way, I may have had drink when posting it in which case it's probably not as helpfull as it could have been
Work safe, and remember all technical problems can be resolved with a hammer, the trick is knowing where to hit it and how big a hammer to use (I often find it may also help to have a spare bit in the shed to replace the bit you have just mullered

)
Work in Progress (or not as the case may be) I give you....
'O-no' the truck.Comments on 'O-no' the truck may be left
hereWork in Progress (or not as the case may be) I give you....
'Truck'Comments on 'Truck' the truck may be left
hereOwning a 2.8 is a hobby in it's self...