I've used Oregon before with no issues. A lot of the internal parts of a TH200 are common with the 200-4R, so upgrades are available. The TH200 has actually become popular for some racing classes since it's so small and light.
TH-200 Transmission: Court Room to Race Track - CIRCLE TRACK WAREHOUSE | PERFORMANCE RACING DISTRIBUTOR | AUTOMOTIVE PARTS
Once a legal headache for GM, the lightweight TH-200 has become a popular solution for both drag and circle track racers.