Now I recall, we were going to try advancing your timing when we discovered it would not run without the hold-down clamp bolted tight. Which I think you still need to address if it still won't run without the clamp and the extra new ground wire after you've cleaned the grounds.
Anyway, forget about the 7* BTDC that the book says. These engines like a little more advance. Sometimes a lot more. For many years I used the old-fashioned timing light that just blinked, no digital nuthin'. When using that light, the BB (let's call the dot the BB) would disappear out of the window at about 17* BTDC. But I have a vacuum gauge. I would advance my timing until I got my highest vacuum reading, then I would back it off (retard) just a hair or two and go drive it. If it "pinged" (sound of pre-detonation) I would retard it another hair. Then one day I got a fancy new timing light, found out that I had been running at 22* BTDC.
today I'm running 30* BTDC no problem.
So, with your engine running, and the dizzy clamp just loose enough so you can rotate the dizzy body with one hand and maybe a timing light in your other hand, and maybe a tachometer you rotate the dizzy body just a little and watch the BB and the RPM. I'm pretty sure that if you rotate the body in a counter-clockwise direction you will be advancing the timing. Your idle RPM might pick up when you do this, if it gets too high, walk around to the carb and turn out the idle speed screw. Then go back and advance the timing some more, just in little bits. That's how I do it, a little timing adjustment, a little carb adjustment. Back & forth. See how much advance your engine likes and if it improves the idle and drivability any.