Working on a '99 Miata. Changed the right rear caliper, but cannot find information on the maximum torque to close the bleed valve screw. My repair manual does not have this information nor the Kragen store nor the website of the manufacturer--Cardone. Any help will be appreciated. Thanks.

Just snug them up by hand, using either an 8 mm or 10 mm combination wrench. No need to do anything more than that. If you do, you run the risk of shearing them off.