The mounting distance for the two arms is the same, but the hole for the RB200 is a couple of mm larger.
The 2m cartridges are a very good match but you will need to raise the arm by2-3mm using a spacer to get it set up properly and this means that there will be very little of the base thread showing underneath the turntable to fix the arm down with.
You can solve both of the problems with one of these:http://www.musicdirect.com/p-7448-rega- ... d-nut.aspx
which will take up the slack in the hole and also screw on properly.
If the turntable came with an RB200 then it's 30 years old and, unless you know it's been recently serviced, it's worth changing the drive belt and cleaning and lubricating the bearing.