By 'original' do you mean 'as stock original' or 'original but I want to stick an air bottle on the back'
Snipers with all original parts are tied to CO2 because of the internals and old spring setup, to run them on air properly you need Nelson springs and newer internals.
Also none of the nice stock setups work with air. If you look at the old advert in the pump gun pictures thread then I can build most of those, you'd have to get your own bottle or 12gm changer and I don't have the L shaped stock or any thompson barrels.