my friend joey at camaster uses rockcliff boards in the mc class routers, i have seen them perform and they will do the trick for a router of this size, you have two issues that probably need addressing
1 ) the shorter gantry plate this may need a spacer or modification in order to get it parallel to the table surface, a decent machinist should be able to help, or show us some pics.
2) the bearings, i would look into the better quality bishopwisecarver bearings of the same type, the nylon/aluminum is i believe what you have and they make a better bearing which should have the same fastening setup.
i would take the motors off and get the tracking correct first, then worry about electrics and motion.
jim
James McGrew CAMaster 508 ATC
www.mcgrewwoodwork.com http://dropc.am/p/EJaKyl