Set as much intial timing as you can with out pinging under load. IE pulling a hill in drive or hammering on it in 2nd. I think I'm around 12 degrees BTDC intial and I get 22 mpg out of mine. You get more power and better mpg with as much timing as it will handle. Run a colder plug then the book calls for too. It helps a bunch. I cant remember the number on my Autolites but compared to a Champion heat range it was around 12. The ones they call for in the book are way too hot. You'll get lots of dieseling on hot days at shutdown. And premature pinging from the hot plugs.

If you dont have a dial back timing light just get a elcheapo Summit brand timing tape for a Mopar 7 1/4" dampner and you can then set it with your standard timing light and also check the total timing at 3000 rpm. The summit tape is around $4. Might be able to find one at your local parts store too. Has to be for a Mopar though. Your total timing should end up somewhere between 34 and 40 degrees I'd guess.