The only ITA VW options are pretty much outclassed, although a full-tilt (e.g., not on the cheapo) 2.0 16v Golf might be an interesting 'challenge.'

The MkII and MkIII Golfs are well positioned in B. I'd recommend the latter, because of their torque and the fact that they are just newer so one generation farther from being a vintage race car. That said, the TRULY affordable answer would be to buy an already prepared MkII 1.8 Golf. There are lots of them around and there's NO way you could duplicate most of them for the money. If you can find someone to help you shop, who knows the rules, you'll be more likely to dodge bad decisions.

Kirk