Yes that combo is legal and fine to use at the club as we use 13.5 brushless motors.
Iv never used one of these speedos before but I'm sure it'll be ok!
A good option is one of these, quite a few lads at the club use them
http://www.giantshark.co.uk/xtreme-stock-p-405301.html
But any speed passion speedo/motor will be a good option