Depending where you are based it may be better to buy from a wholesaler such as Cousin here in the U.K, you say the clock is fitted with a pendulum so you will need a movement with a drive unit built in for the pendulum. As far as repair goes clock repairers would not waste time trying to they would just do a straight swap out of the movement, you need to identify the movement fitted cousins have Hermle and Seiko versions available:
Also bare in mind that you would need one with the correct shaft size.
I pulled this off of the internet:
An India Stone is made from the man-made abrasive aluminum oxide. The term India Stone is a trade name for Norton's Aluminum Oxide sharpening stones. Norton's India stones are orange, tan or brown in color. This distinguishes them from Norton's Crystolon (silicon carbide) Stones which are gray in color.