If you fear that much about total carnage, then you shouldn't use it!!!
Well, The guys in RC Car actions (A Yankee RC Car magazine) had done it few months back. Putting a 5 turn Brushless in the M03. and manage to get close to 94km/h. so there you go......
but for a M car to put brushless engine. many of the people who driven one before complain about the stiffness of the car at the front, and the tail is a bit loose. also excessive understeering of the car itself. so if you want to try it. make sure you have that in mind........
5.5R ???? So fast for M03 la.... not the problem of running performace, is the plastic classic not strong enough for so high speed........... the gear box will..........HAHAHA!!!! and have you consider about the gear ratio???? what gear ratio you willing to use???? an not correct gear ratio will cause over heat or damage of the brushless.....