[Mark Henry]

I also set it on the fly with a strobe. I set the dizzy to #1 best guess, loosen the dizzy just enough to move it, fire it up and then dial in the timing. I'd stick to 27 degrees total at 3500rpm with carbs. I can get it in the ballpark within seconds of it firing up.
When I did the 3.0 Webers with a twin plug dizzy in my 914, my then 15 year old son set the timing in seconds. I checked his work and it was spot on and it was the first time he'd ever done this job.
For carbs I use a wide band O2 meter, you know instantly if you're jetting is too lean or rich. You don't want to be running lean on break in. Both of my meters were the same nominal readings, so you only really need one meter and one exhaust bung welded in. Many do two meters/bungs as I did, but I took the one meter out and only use the one now.
I also use a head temp sensor (Micro1000 round from aircraftspruce), too hot and you're again likely too lean.

Even my aftermarket EFI/crankfire (different engine) you still have use a strobe to get a baseline of 10 degrees BTDC on the fly, only difference is the adjustments are made through the computer.