lol I find mk4 engines go better in a mk3 also

No doubt would go even better in a mk2 but I prefer the mk3 comfort. I have a mate who has a custom 2.1l, forget what its made up of but its pretty quick, fun to have a ride in it but as a daily no thx far too uncomfortable

I think the rust issues are about how well they have been looked after with how old they are (obviously), but what I mean is, most if not all the badly looked after mk1/2s will have rusted out and been scrapped by now so you only really see the ones that have been looked after. A badly looked after mk3 would still have enough life left in it to be on the road

At least thats what I'm putting it down to
