...and this is the problem with Chumpcar
I've been working with a number of teams up in this part of the woods. It's not so much about the car as it is your knowledge. We run a double 8 and a 24 in Spokane. Reliability is almost out the window with that kind of beating every year on these old cars.
Go with a platform you know inside out and have lots of spares on hand. You will break something. Maybe many things. If you have absolute knowledge of the car, you can resolve these issues fast at the track and get back to racing. Bring lots of tools. Like your whole shop + a generator. Two years ago, I was welding in an empty field next to the paddock at 3am, it can get that nuts.
Also, SIMPLIFY SIMPLIFY SIMPLIFY. I'd say it again, but I think you get the point. If it doesn't make the car go, turn or stop, rip it out. It'll just break on you and cost you time.
Get it to the track before the races! Nothing like a good 6 hours of shake down time before you go into competition to find those silly little things you couldn't expect on a 30 year old car. That, and it'll give your team an opportunity to get used to the car and hopefully the track you'll be competing on. For us, first race isn't until spring. We'll be heading out end of this month for our first track day.
I'm prepping a 944 for next year. NO upgrades on the car. The nice thing with Porsches, there's already a race car under there somewhere, you just have to get rid of everything that's not race car. There's only 2 vacuum lines on mine
Set up properly, it should be as dependable as anything else out there.
Last, team organization is everything. Nothing makes a car go faster than a well organized team. To this end, I'm not driving next year. My job is planning, organization and logistics. At the track, I'll be running around dealing with the stewards, managing sleep schedules, food, fuel, lap time targets and screaming on the radio for 24 hours straight. You NEED someone who not only can do this, but wants to do this.