aku: 3R uses different front/rear teeth pulley.i can't recall the numbers but the rear diff pulley is a lot smaller than v1r pulley and the front is a tad smaller. Anyway the internal ratio of 3R is 2.0 while V1R is 2.53.
as for engine mount, 3R uses FW05R engine mount, just for your infomation, the engine mount actually 0.5mm lower than kawahara low CG engine mount.
Just to point out not all engine mount from different brand/model are compatible with one another. The hole patterns for engine to be mounted on engine mount are the same but the hole patterns of engine mount to chassis can be different between brand.