I ended up making a stock Mopar low deck electronic distributer work very well in my old pump gas Duster by shortening up the advance slots so it had right at 18 crankshaft degrees of mechanical advance, which is nine distributor degrees, all in by 1200 RPM. It would start well and idle at 850 RPM in gear with 16 degrees BTDC, a fairly big solid roller cam (260@.050 int. with 266@.050 on the exhaust lobes installed at 106 ILC) ground on a 108 LSA.
That car and motor made me very happy, made some money at the track and had a lot of fun with it on the street

I don't doubt it, Cab. Id probably be fine w an advance curve too, but I need a guru like yourself to get it all dialed in!

What springs did you use so the advance to be all-in at 1200 but none at 850 (or very close to it, since otherwise the idle would be unstable with changing advance)?

Back then I used a pair(the thinnest, weakest set) of springs from a Mr. Gasket kit, I don't remember the kit number now though
Those springs would pull the advance weights back under 1100 RPM and be at full advance by 1300 RPM which made the motor start well and t was like having the distributor lock out almost.
It took me a while to figure out how much initial to set that motor up with so it would idle well and not kick back on the starter, it would start to kick back at 18 BTDC would really kick back at 20 BTDC 13 BTDC or less made it not idle well

You can maybe try contacting Joe White and have a custom mopar one set up to the curve you need. He does great work and many people have said very good things about his distributors. Joes mopar distributor restoration on facebook is where to find him. I had him do a cable drive electronic one for my 493 and am very happy with it

I've never done this, but these discussions usually make me think.

If a person was trying to thread that needle, get the engine to spin and fire at one RPM and timing setting, then have the ignition go to near total or total when it starts so the dumb thing will idle and respond... why not use distributor advance flyweight weights to adjust it?

Springs only give you a few options. Weight changes can be infinite. They do it with clutches.

Add a dab of spot weld with a MIG out on the heavy end of the weight. Get too much you can grind it off. Or drill and tap some machine screw holes and add screws and washers. More weight should bring advance in quicker. Keep the flyweights equal.

I would want to do this on a distributor machine. Probably be a PIA trying to do it on an engine.

TonyS451 I sent you a PM. easier to talk on phone than type it out.

Tony I fought with this a few years ago after changing to a digital 6 plus box from a old analog 6AL. Mine would kick back on the starter about 1 in 4 starts.

With the digital 6 box and HVC coil I had NO improvements just shorter cap and rotor life and shorter plug life on a indy headed 12:1 427cu in small block on e85.

I went back to the analog MSD 6AL stating issue went away, cap and rotor life improved, same ET and MPH. My personal opinion is the Digital 6 box is a POS.

Try something else

I guess every engine combo is different as to what it "likes".
My 451 (currently iron-head 10.3:1) doesn't fight the starter hot until 24 degrees initial.

So I ended up with one super-light spring, and one OEM heavy spring with loop in an OEM reluctor-pickup distributor.
This cranks at about 16 initial for easy starting, immediately goes to 27 at idle (1100-1200 rpm), then a slow increase to 35@4000 (as high as I've checked). The rotor tower is an 11/22 degree unit, so max advance is limited to 16+22 = 38

Since I drive it on the street, I also use vacuum advance, something like 15 extra degrees at a 15" Hg. cruise. Obviously not a factor at starting or WOT.

I've had a couple others say the say thing.. I do have a 6al sitting around... Did you also use the separate starter saver?

I use an Ice Ignition system with the volt booster. It is an inductive system and the booster keeps 16volts at the coil. It is a 7amp box with a two step and 10* start retard. I have a short curve in it, 30* at 1400rpm idle and all in at 36*@2500rpm. Works really nice like that. If i lock it out i sometimes get a kick back when hot and the timing retards with rpm about 3 or 4*, Its the nature of the beast when using only a distributor. Check yours, i bet it does the same at about 2500-4000rpm. Put a crank trigger on it and timing will be rock steady at any rpm and the timing has to be locked with this system. Hope this helps

What affects "fighting the starter":
CCP
Flywheel or converter weight (actually inertial mass)
Number of cylinders
Rod ratio

There is also another "RPM vs. spark position" in addition to centrifugal with vs. spring tension: tha shape of the weight. Examine a GM (easier to find) plot of engine speed vs curve and you'll notice that the curve is distorted (made non-linear) by the point where the weight’s concave radius contacts the center plate, which changes as the weights move. The weight normally acts against the gradually tapered side of the center plate. However, at very high RPM it continues to advance at a much slower rate, which may not be detected but may be enough to cause damage.

No I didn't, my combo did not care care, normally locked out at 34btc.