Are the adjustable coilovers that significant of an upgrade over the stock ones? My thought process is to throw as much tire under the fenders as I can possibly do. I thought the aftermarket versions were more so for lowering the Sky.
The aftermarket coil overs allow you to change out springs for different rates and adjust rebound and compression...separately if you wish. I have found the adjustability (though mine are a single adjustment for rebound/compression instead of one adjustment for each individually) to be beneficial in dialing in the balance front to rear just so. If you are around stock weight, 275 is the perfect width for these cars. The SCCA teams back in the late 2000s ran that size and most who race these cars will tell you that's the perfect width for them. I'm still waiting on getting a set of 18" wheels wide enough to fit 275s on them. PAW has a selection of race wheels wide enough for that width and designed with an offset and bolt pattern to fit them on our cars without clearance issues.
I have been looking into the local SCCA course rules and they don't state cages are necessary. To get my Novice Permit I will have to go to Virginia and from I understand the rules are up to the instructor.
You have to look at the rules concerning convertibles. Most state that unless the convertible has built in roll protection behind the driver's head from the factory, a roll bar must be added. Most track rules are this way too.
That said, some tracks will ignore that requirement and let us run our cars without one. It can be hit or miss though. Sounds like your local track may be like this. None of mine (California Speedway and Willow Springs) are.
Will the RPM bar make you lose a lot of space behind the seats? I am 6feet tall and I slam the seat as far back for longer rides. My head is above the head rest as well. Would you say the bar is 3 or 6 inches above the seat?
I am 6'1" but have never sat in a car with the RPM bar. From all the bars I've seen though, it is the only one that will let you put your OEM seat all the way back without interfering with it. As for head room, put on your helmet and get in the car with the top up and see where you fit. The RPM bar is designed to allow you to have it on with the top up IIRC.
I have looked at your older posts and plan on getting Hawks HPS pads.
They're good pads and it wouldn't be a bad idea to swap out to braided lines and brake fluid designed for high operating temperatures. I mean, it's probably time to swap out the fluid anyway and you can have braided lines made for under $50 per line.