Grinding fins off of a Neu 1515 2.5D - OK?

[JThiessen]

I'm finally got to the stage of installing the Neu in my conversion Revo. I have the GMaxx single speed conversion on the 3906 tranny, on which I have the Revo spec slipper system. According to the calculator, I need to be geared at about 50-56/25-30. I installed a 54 tooth Jato spur, and have a 30 tooth pinion. However, the gears just barely touch with the motor all the way against the tranny. I think that if I grind off the fins, and maybe a little on the tranny, I can get it to mesh. Anyone else run into this? Will it affect the structural integrity of the can?
Thanks