If you want to remove alot of metal, your best bet in a NORTON Stone CUP wheel. Once that is done, go to a 36 grit disc, then a 50 grit, 80 grit, and finish with a 100 grit. All Made By NORTON.
As for build up rod, Hard facing rods are for abrasion, more than Impact. I used Mangenese rod to build up mine, and after 15 years, it is still holding up good.
I hope this helps.