Jim, sounds like you have a couple of type 5N's. I believe you'll find that for a V8 application the gears are not exactly optimal. You can read about many people's experiences on this transaxle forum.
You might be interested in a new ring and pinion that lowers all the ratios. You can read all about it on the following thread: http://www.gt40s.com/ubbthreads/show...0/page/0#57684
Enjoy, and welcome to the GT40's forum. There's so much to read, you'll always learn something!