Yup, sounds right to me. Maybe some engine builders like to build an engine a little differently for the 3 pipe, can’t remember, but you can throw the 3 pipe on there with no issues. Carb settings are the same, around 2 – 2 1/4 on the low and 1/8 to 1/4 on the high. Not sure how you have your carb setup now, but usually we’d start the low at 1 1/2 on the grid to get rolling and once we started getting up to speed we’d open to 2 or 2 1/4.
Header is the same.
Classified section is a bit empty at the moment. Check your local shop or with other guys at the track who run the class. I’m sure at least one of them has a collection of used 3 pipes laying around.