A mk1 can handle a k03 20vt fine and can muller a lot of cars below 80 (with the suspension and brakes done of course) and you get sheds more punch than a 16v - they are an absolute hoot. I agree a k04 would be a bit too much for the agricultural chassis. Maybe I'm getting old but I dont miss my old one and prefer a modded ed30
Rosy specs off, they feel very old to drive as standard.