32 seems to be what the manuals call for, but I've had individual motors vary greatly. My 88 stroker does ping on 32, I'm in the process of dialing it back to the happy medium where it pulls well with no pinging.
For normal 80's I'd say that "F's" numbers are about right. I've played with the manual advance for years, on the flathead it seems to just shift the power band up and down the rpm range. More retarded for low end grunt, advance to lose some low end, gain the power in high end. ( I realize that "high end" is relative when speaking of flatheads !)
I made an attempt to create my own electronic advance unit awhile back, and had decided that a linear gradual increase of advance from idle 7-800 to about 2500 would be a good compromise.
As a final note, I got a hold of a 45 auto unit last year and tried that. It had very weak springs, and advance kicked in very quickly. I'd swear it was fully advanced by 1000 rpm's. basically just used to avoid kick back damaging the electric start.
Unfortunately, I didn't have a chance to measure the full range of advance of the unit before I got rid of it.
I think the old timers only used to retard the motor for starting and pulling stumps on the back 40.