Tune-up Specs

I decided to check a few ignition specs on my 390 over this past weekend and to my surprise I could not find a clear spec on ignition timing and spark plug gap.  Is there no standard for these items?  I live in Kentucky about 1000 feet above sea level and usually run 93 octane.  However I was told that the compression ratio had been purposely reduced to afford use of regular gas, however, let me not digress.  Currently the motor is running autolite 66 spark plugs which were gapped from 33 - 46 thousands.  I re-gapped them all at 40.  Plugs were a little black so I imagine the motor could be leaned out a bit.  I have no idea if running a DUI distributor has any bearing on gap or timing.  I should say that timing, without vacuum connected, looked to be a couple degrees advanced.   I reset it to 6 or 7 degrees.  Motor seems to run fine but once again I just pulled the gap and timing from settings I remember using to initially set up old BB mopars.   Can anyone give me some good starting points?  I even have an AMC shop manual that didn't specify these basic settings.  Of course I'm getting old and can't see as well as I used too so I could have missed this info.

FWIW the 70 TSM has:

IB Sorgn wrote: WesternRed wrote: FWIW the 70 TSM has: Type 1 distributor 5 +/- 1 BTDC at 500 rpm with vacuum disconnected and 34 +/- 3.5 at 2000 rpm with vacuum connected Type 2 distributor  TDC +/- 1 at 500 rpm with vacuum disconnected and 45 +/- 4 at 2000 rpm with vacuum connected What is a type 1 or type 2 distributor?   What is your source for timing settings?  Would like to read.

Type I distributor has 2 vacuum cannisters One advance and one retard). Type II has 1.

Trader wrote: So the motor is not factory, why try to use factory specifications? Best you can do is advance timing or lean out just a little at a time until you find hesitation or light detonation and then back off. Running a little rich is far better then running lean. You break things running lean.

IB Sorgn wrote: Sonic Silver wrote: It is in the 1970 Technical Service Manual or TSM that Red mentioned. American Motors 1969 Technical Service Manual

Red mentioned both Type I and Type 2 distributors. Type 2 didn't come out until Sept. 26, 1969, so it wasn't available until the 1970 model year. Therefore it is not listed in the 1969 TSM, which covers only the 1969 models.