A few things....

A larger spur in combination with smaller pinion than what comes stock in the kit will lower the output, and will be slower, but conversely, speed is not a concern with drifting, as smoothness is the most important factor.

There are differences when talking about 48P and 64P gears. 64P will be MUCH smoother, with less gear noise, but prone to damage from grit. pebbles, rocks, etc., much easier than 48P. I, myself, prefer 64P, because I drift in clean swept areas, so grit, pebbles, etc., aren't a concern.

The big thing here is, to match the gearing with the power system, which makes power system choice important. I have recommended the 17.5T BL for drift everywhere, yet am inundated with those who believe they know better, and get overpowered systems. I tend not to talk to those people, when they begin asking for solutions, when they find their choice a bad one, but will not correct it. Yours, as stated earlier, is not ideal, but not so overpowered, that it can't be compensated. Your spur choice is a good one, so you're well on your way to making your TA06 perform the way it should.
Just remember.....once the proper motor choice is made, gearing is used primarily to make small adjustments to power delivery, to suit the driver's preferences. In your case, the power system is only slightly overpowered, so your compensation won't be much, but your adjustment parameters are smaller, because the extra power of the 13.5T take up the upper half of that adjustment range, follow?
It's why the spur choice you are contemplating is a good one, coupled with a smaller pinion. You might even go smaller on the pinion, but experiment, and see which combination works for you.