Customs 51ply shock problem

I have a 51 ply. concord kustom. I have installed lowered front springs from Eaton
Springs. I have also made a new upper shock mount that is welded to the frame.It looks
good but rides rough. I put gas shocks on it, but talked to the Eaton Spring man at the
G.G. Columbus show last weekend. He said not to put gas shock but to use hydraulic
shock. No Gas. Where can I find them without spending a fortune. Any help is
appreciated., Thanks