Some, perhaps all of you will laugh and my next 2 suggestions don't fit the vintage criterea. A Nissan pickup that has been lowered about 2" inches overall and a set of lower profile tires on a bigger rim does very well and will surprise many more powerful cars in peformance. I raced my last pickup in the above configuration in SCCA Solo Two events for a couple of years with amazing results. Alot of times I was getting as good or even better times than Cameros, Mustangs, Firebirds and Corvettes and had no problem staying with the smaller RWD formats either (Miatas& Cellicas). I currently drive a beat up bone stock Nissan pickup like I stole it everyday and have a blast doing it. If you know nothing of Solo events they usually favor smaller cars and front wheel drive. My second suggestion is the Dodge Omni GLH Turbo or Charger Turbo especially the Shelby versions easily matches the straight line performance of the V-8's of its day and drives like its on rails. I had a non turbo version and loved it, run off many a 305 Iroc/Z28 and earlier 80's Mustangs with it. Transmissions are hard to keep in em though. Oh heres another suggestion but out of the price requirements. The GMC Cyclones and Typhoons.
HF