I have owned the Interspace with Rega arm and assume they have not changed it in the meantime.
As you may or may not know the armboard is attached to the plinth with two screws. The plinth has two rows of holes. The arm to spindle distances is variable by increments determined by the distance between the holes, so you do not need a new armboard. However, there are different sizes of collars that insert in to the armboard. Rega's arm posts have a larger diameter than the Interspace arm posts, so the Rega arm will not fit in to the Interspace arm collar. The collar made for the Rega arm is necessary for proper installation.
I obtained mine from my dealer. Audiophile Systems Limited is an uncooperative importer, and Nottingham effectively runs at turtle speed, so I would caution you to make sure you can obtain the collar before purchasing. That would be my situation if I were in your shoes, but I do not have any knowledge of how to obtain a collar any other way. Good luck. It is a great TT value.
As you may or may not know the armboard is attached to the plinth with two screws. The plinth has two rows of holes. The arm to spindle distances is variable by increments determined by the distance between the holes, so you do not need a new armboard. However, there are different sizes of collars that insert in to the armboard. Rega's arm posts have a larger diameter than the Interspace arm posts, so the Rega arm will not fit in to the Interspace arm collar. The collar made for the Rega arm is necessary for proper installation.
I obtained mine from my dealer. Audiophile Systems Limited is an uncooperative importer, and Nottingham effectively runs at turtle speed, so I would caution you to make sure you can obtain the collar before purchasing. That would be my situation if I were in your shoes, but I do not have any knowledge of how to obtain a collar any other way. Good luck. It is a great TT value.