Engine Dieseling - Options?

I was able to do a little check tonight - got the engine warm and checked for vacuum leaks - nothing shows up any where - good and bad I guess but will eliminate that as an issue - next I backed everything off on the carb, mixture screws front to 3/4 and rears to a 1/4, idle screw backed off completely, reset timing to 20 - idle down to around 900, vacuum now moving between 7 and 9, not jumpy or fluttering though. heavy rpm drop when going into gear, exhaust smells a little rich still - dieseling was nearly gone, cranking still ok with no kickback. Looks like I will find a decent spot for initial from 16 to 20, so looks like Im heading in the right direction, I would be OK driving as is to go top off the gas tank and finish diluting the octane boost juice down. starting to hope again I can tune out and run on pump gas - Im gonna get back at it this weekend, first thing is the carb is coming off for a good thorough inspection if I can get a rebuild kit with all the gaskets, may even re-jet my 670 and put in on there - it has been a proven performer on my Mustang - thanks for all the info - will see what I can do with a little refresh of thinking
Glad to hear you are making progress.
LIke I mentioned before this is a balancing act with the idle mixture screws and timing dont get frustrated take baby steps in the process and you will get it.
Like Rusty said use a vacuum gauge to set the mixture screws - SLOWLY.
There is most likely nothing wrong with your carb gutting it know is just going to throw a curve in your tuning process. I would work with what you got.