Unless it's a complete bag of sh!t, you've got a good deal there.
I get anything from 32 running about, to 38 MPG distance, so expect similar.
Watch out for the rust!

On the SWB, watch the sills and seam against the rear wheelarch leading edge, the whole of the underside, rear door shuts, roof seams, etc.......
Door shells seem ok though. These are going to be as bad as any previous Transit me thinks
