I got the newer shape 2008 I managed to fit Renault Espace leather seats in the front. Used the current driver sub frame which needed to have two new holes drilled to fit the seat and runners.
Passangers seat needed a subframe and some serious work. I couldn't get a sub frame to fit or the correct height so I took a low sub frame from a reanult van there are two types a low one or a full height box frame type, you want the low open one but measure up first. Once I got that fitted only two bolts would connect using the original mounting supports so I made an extension to the sub frame using 5mm steal and created a bracket I bolted and welded that to the renault sub frame and then fitted to all original mounting points.
Runners needed to be drilled again to fit the seat.
I did want to have a swivel chair but the way the hand brake is fitted id need to take the hand break off to spin around, if I take the arm rests off there is just enough room to squeeze through to get into the back. If I done it again I think id make the passanger a swivel and keep the captains chair fixed rather than both fixed.
Good luck - if you do fit seats in best advice I can give you is to use self locking nuts and tighten everything up with an impact driver, I found even if I done everything as tight as i could, one rock in the chair and the thing felt loose, since changing the nuts to the nylon type I've had no issues and has never been an isse on an MOT test..