A MK1 caddy drove past me earlier in Swansea, I’d love one.
I believe you can pretty much wang in any engine that came in any of the MK1’s so a 1.8GTi engine would be my choice, electromechanical injection system so no worries about ECUs or such. A 16v from a Mk2 would be temping, but I believe that means trying to find the rare right-hand intake manifold from a Sirocco 16v which is almost mythical it’s so rare.
I believe the biggest challenges to people who really love them and want to build really nice ones is finding a embossed tailgate that’s not dented or rusty because VW only sold plain ones as spares and finding nicer seats – the standard ones are flat, boring and not veryu comfortable, but you can’t simply throw in a set of GTi seats because the cabin is so short they won’t fit unless you’re very short.