Super Six, Slant Six Timing

Just finished the motor swap on my '67 Dart. Swapped in a slant six from a '69 Dart.

Currently I have the carter two barrel super six set up. Distributor is stock with points.

When I got the motor it was two teeth out of time. Getting ready to work on the timing and wanted to know best practices. Trying to get the best gas mileage with a 904 and still have some jump.

Where should I be looking at as initial degrees at idle and onward from there?

Should I be disconnecting vacuum advance during the whole process or part?

I also have a spare tach laying around should I be using that as well to get as accurate as possible.

I know ultimately HEI is the way to go and it's in the works this winter. Until then I just want a fun realiable motor to get me through the summer.
Im really good at the nuts and bolts part and eager to learn the more technical aspects.

Thanks!