Sounds fun. Your new Miata sounds like a beast. I recall people used to put the 89 - 91 5.0 Mustang engines in them but I heard they are nose heavy. Yours sounds more balanced.
Open track events would be Sears Point / Infinity Raceway and Thunder Hill are the two main areas that are close to me. I used to run in the beginner groups. My wife's requirement for me was easy - I have to be able to walk away physically and financially So that would limit me to 1 or 2 evens a year, track insurance, etc. I was using my daily driver anyway which was a 89 LX back in 2001 - 2003 and recently 2015 GT/PP with minor suspension adjustments. GT350R springs, steeda adjustable struts, few bushings. Basically firming it up but maintaining daily driver ride comfort. It was also our touring call if you will. Trips like Sacramento to Vegas to LA and back. Was planning Sacramento to Key West Florida Unfortunately I sold the car last year. Considering a used GT350 but probably not in the cards...
I'd love to do the western tracks, but probably not in the cards for me. Now that the wife is retired we are doing a lot more traveling and some of it is pretty expensive. Fall of 2020 I talked the wife into a week long snorkel trip in Fiji with a group called Road Scholars. We've already done 2 trips with them (Albuquerque Hot Air Balloon Fiesta and Churchill Manitoba Northern Lights) and have 2 more already scheduled. Next is this fall to Moab, Utah to photograph Arches and Canyonland National Parks with a professional photographer/instructor.