MST XXX-D VIP Gearing Help

Hey all, I was blessed to have traded an old rig for a MST XXX-D VIP roller. Added stealth mounts and transferred all my electronics and wheels.  I learned that this has a 64P spur. What is the stick gearing for the chassis? I had a friend give me a 64P 26T pinion but not sure what the proper gearing should be. I tried to Google it but did not get a proper answer. 

Also, did anyone with this chassis change the gearing to 48P?

Here is a quick pic of the chassis.  Live it! 




Thanks for the help.