my experience of 'repairing' gearbox is basically replacing each/some of your gear bearing...and the output will be your gearbox will be more noisy...reason very simply...imagine now you said your 3rd gear is bit loose etc...and you only replacing your 3rd gear bearing and so call 'tighten' it...same time it pressured your others gear which the gigi already makan....
SO in order to rectify this, you basically need a brand new gearbox where all 5 gears, reverse gear, bearing, shaft all new...else no point fixing them...
A Rm2000+ to me is a halfcut gearbox...recond or not...depend your luck... i would spend looking for one which is from halfcut and look at the external case condtion and all the gear level...to 'try' guess the condition...final outcome only know once you installed into your car...but certain necessary need change like flywheel bearing etc...
BTw, what problem with your 1.6 gearbox ? 5th kick ? make sure you get the SAME code gearbox as ratio is different...SOHC, DOHC, Mivec....