It's common for LHS to sell what they have. Mine is that way, too. They know me as someone who is particular (seeing as I'm the only one who goes there that orders on-road stuff) about what I buy, so don't even try to sell me things they know I don't need. The owner sometimes gets something he thinks I'll be interested in, and he's become pretty good at knowing what I want.
As I say, you can easily work with the 13.5T motor, just gear down. To do that, just get the largest spur and small pinion that will fit on your TA06. Whether 48 or 64 pitch, the way you tell about gear reduction is, the spur will be large, and the pinion small. You know what comes stock, so just go from there. Easy-peasy! I gave up "speed at all costs" a while ago. Nothing is more sobering than seeing a $1,000 RC car slam into a curb, and turn itself into bits of plastic and bent metal, at 65 MPH to 0 in a millisecond.
I can laugh about it now!
So.....I just use power systems that are a bit slower, and to be completely honest, more fun! It's a challenge, to get the right power system for whatever discipline, and for drift, it is the slower systems that do the best. I also do some track racing when can, with front wheel drive minis, or 1/12th scale. I'm working on a couple, now. They ARE fun! Not very fast, but they don't have to be - they look like cockroaches scurrying for cover, when ontrack! Once I saw an "M" class race on Youtube, I was hooked! I have been doing that, now, for three years, and will never give up my "M" class cars.
64 pitch is only good for less noise. I like it, because of that. My chassis are fairly quiet to begin with, so 64 pitch gears just enhance that. It's a good thing to take advantage of, so if something does go wrong, you can easily tell, just by the sound. It's the diameter of the gears that delineate what your FDR is. The tooth count is the way to tell what it is, by number.
Blog? Me? Nah.....I'm just an old guy who loves working on RC cars!
I don't mind helping out how I can, and am particular about who I can help, because so many act like they know better than everyone else, or are into their own work, which, in the scheme of things isn't so bad, but I'm just not into "tooting my own horn," if you know what I mean.