With the 727 you can cheat with a climb anyway. I do this by pressing CTRL+SHIFT+Z then plus (+) or minus (-) - the keyboard shortcut for A/P Altitude bug (select). Of course I have to count each press of the plus or minus (not good if you press to quickly) to get an idea of the altitude I am setting it to, so I prefer to use that when I haven't clicked on the Altitude Hold button at the correct time so I am only 100 feet off (one press of plus or minus). You at least get to enter the actual altitude that you want it to hold/climb to and hold.
;D