AC and idle in a 1970

[davepl]

My 1970 402 has factory air; when you turn on the AC, naturally the RPMs drop and sometimes, if you don't have an artificially high idle to start with, it wants to die.

There's nothing I can see on the 1970 that bumps the throttle up, and if you just run a higher idle, there's no anti-diesel relay that I know of for 1970.

So what's the deal with the 1970? What's the right way to balance this whole "higher idle to handle the AC kicking in, but not so much that it diesels when you turn it off?"