You cant just pop in the new seats as the underside is different. You'll need to mod the mk3 seats to fit the mk2 runners. Also you'll need to mod the rear bench fixings slightly too. Plenty of 'how to' guides to do this on the web. Regarding seating height I'm pretty sure the seats are just the same, barr the mk3's will no doubt look better. You probably could mod them to sit lower, but will be more hassle than its worth.