That 250 at the wheels will all depend on what tire you choose for the track. f you are serious about tracking your car, I'd go with something that has a bit more customization such as different k rated springs, and dampening control. This way you are able to dial in what you are comfortable with as you advance in learning how to professionally drive.
The Racelands do no have adjustable dampening and only one set of springs for the coilovers. So you are limiting you self at these rates when you go out to the track and might end up pushing yourself to try to make the suspension work for you and not with you.
They don't have rear camber plates but I'm using the GD ones and they fit not problem. Only thing is you have to zip tie the brake lines to the coilover, but that is easy
Yeah they only have one set of springs out right now for them which are the 450 and 280 spring rates