Subframes from a Mk3/3.5 fiesta are whats needed mate (the Ugly one). I had some in my old Puma with 90's spec Recaro's fitted, but like an idiot sold them on when the Puma went. I now have another Puma so regretting the decision MUCH! They do pop up on ebay from time to time, alternatively try and find some basic Fiesta seats and cut off the subframes (my plan), the basic seats from a Fiesta dont have all the complicated workings with the adjustable base the Puma seats have so they are easier to cut off and weld up. Alternatively you can buy some ready made I believe but when I last looked they are £££££££££££