Check out the first post of this thread. You will see that in the rules of the 300mph Club, wheelies are not allowed (look here if you want
wheelie trick speeds). Additionally, speeds over 350mph require video proof (which is easy once the PS2 is connected to a computer, just as you intend to do). Speeds also need to be of the session record screen, and shown in MPH. I don't mean to sound harsh or aggressive, it's just that the 300mph club can be quite competitive for some of the regular high speed tuners, and so rules are needed to make sure that all members have the same chance when competing for records.
Raise the front downforce until the car doesn't wheelie and change your game display to MPH; then you'll be a legitimate 300mph club member (You won't lose 50 odd mph from doing this). Looking forward to seeing what you can come up with! 👍