Profoxcg,
The MO5 can be fitted with the Ride/3Racing speed gear set and you then fit a 24 tooth pinion to the motor. This will give a roll out/FDR very close to the maximum of the ABC Grid. The ABC Grid, however will still be a little faster.
This setup is used in Thailand at the TITC event which is held yearly. The speed gear set MO5 cars use a Speedpassion Citrix ESC and 17.5 fixed time motor or the Hobbywing system which is the same. The weight limit for the car is 1200 gms with cutting and shutting allowed.
I would also look at modifying the MO5 so it will handle better. I am not sure what your rules are, however if ABC Grids are being used then TCS rules will not apply.
I myself would most likely just purchase a ABC Grid and go out and have fun. I ran the ABC Grid earlier this year at TITC and had a ball. The car was very good and I managed to qualify fifth in the B. I am by no means a gun driver, but learnt alot from my experience.
Anyway the decision is yours to make. I will advise though, the 3Racing/Ride speed gear set need to be run inas they have a small binding point. The other option if you can find them is the speed gear from ABR.
Anyway have fun.
Regards,
Calvin.