The rules are literally what is written:
2.1: Vehicle Eligibility: Entry limited to mass-produced, four-wheeled vehicles legal for US highway use at the time of their manufacture. Vehicles must be acquired and prepared for a maximum of $500 as described in Section 4. Vehicles must meet all safety standards laid out in Section 3. The vehicle’s original, manufacturer-stated curb weight may not exceed 4200 pounds.
That’s it. The less cheaty the motor the less they’ll give a damn about how you got it or what it cost.
The only penalty for over budget is penalty laps on the timing system, which mean nothing since you won’t win on your first race anyways.
As for Tech, fix any holes, re-enforce cage and seat mounting areas to overcome rust issues, and follow the short and very easy to read rules, including the “how not to fail tech” pdf.
Mistake By The Lake Racing (MBTL)
88 Thunderbird "THUNDERBIRDS ARE GO!"
A&D: 2014 Sebrings at Sebring (NSF), 2014 NJMP2 Jurassic Park (SpeedyCop), 2012 Summit Point J30 (PiNuts)
2018 Route Sucky-Suck Rally Miata.