Spectra type watermaker from parts

[Boatguy30]

I ran into a guy last winter that had a built a Clark pump water maker for around $1500. He had bought a used spectra pump and sent it to spectra for a refurb which I guess was around $400 at the time.

I recently purchased what is supposedly a rebuilt, never used Catalina 380 Clark pump. so I need to work out what other components I need.

First off, it appears spectra uses a 20" housing. Now the other guy told me he was using a 40" membrane on a single shurflo pump. Now I assume he meant a 21" as I think the 40 would we way to big. I already have a filter housing and some of the valves but will need an accumulator and pressure gauge.

Just looking for some ideas on how to best lay this out. I am going to go with strict manual control. I don't currently have pressure water on the boat so ill just do the fill a bucket for the fresh water flush initially, but may at some point plumb in my one freshwater tank for the flush and only every use that tank for water maker water as I don't want to hassle with the charcoal filter and all that.

Your thoughts appreciated.