I have a few thoughts. From my recall, your tap drills for 3/4"-10 and 7/9"-9 are small, which will make the tapping torque and stress go way up. 21/32" is the standard tap drill for 3/4"-10 and 49/64" for 7/8"-9. That's 1/32" different than 47/64, which is a lot of extra material for the tap to cut. Three fluted drills are for cast iron and sometimes aluminum and are considered weak for steel drilling. Two flute drills with split point are the way to go, whether it's HSS, cobalt or carbide. Flood coolant should be fine if you have some soluble oil in it. (not full synthetic) 10% concentration is a lot better for tapping than 6%, which is often the case. It can mean the difference between a borken tap and not. What kind of machine do you have? Is it 40 or 50 taper? geared head? A lot of 40 taper machines can't push a 1" drill at the correct feedrate without a 1/2" hole drilled to begine with. If I weren't doing holes in the high hundreds, I would just use cobalt split point screw machine length drills. This eliminates center drills and a tool change. Are the holes through? Spiral point taps are the only way to go for that. If you want to make a ton of holes fast, consider a Tialn coated carbide split point drill like a Garr or Titex.