Silly question this but just to clear any doubt in my mind, I have fitted the 300lb rating springs to the rear and the lighter 200lb springs to the front on my MK Indy-Blade that is right isn't it.

I think you'll be wanting the stronger springs on the front of the car. Also, those ratings seem quite high for a BEC (from what I've read before).

Did MK supply them with the kit?

Yes, the springs were supplied with the kit by MK

Aren't those rated springs for a CEC?

Not sure, I will call MK in the morning to find out.

Check your other (duplicate) post