According to my manual, it's 1700-1900 RPM (Job 7.2-100).

And I stand corrected. The manual adds in Step 11:

"[Re]-attach vacuum hose. Engage driving position on automatic transmission, set to specified speed [600-700] RPM by means of adjusting nut [on vacuum rod]. Turn power steering to full lock and engage AC system. Engine should still run smoothly. Re-adjust speed if required."

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe