I would recommend not using the kit 48P spur and getting a 64P spur and pinion set. I don't run mod so you will have to determine your FDR requirements for your track based the Novak gear chart found here
will point you in the right direction for a starting point which looks like 10.5. With a 100/19 you will have a good starting point.
I recommend 64P because you will find that fitting large 48P pinion and spurs is limited space wise on this platform.