I dug through my PileO'Stuff and found my old notes on video timing. So here are the real numbers:

1) Pixel clock is 15.6672MHz (= 2 x 7.8336MHz). You can use both edges of the CPU clock (if 50% duty cycle) or use the raw 15.7662MHz clock (or regenerate it yourself).

2) Horizontal line frequency is 22.25kHz (44.93us).

3) Frame rate is 60.15Hz (16.626ms).

Hope these numbers help some.

[Oh, and yes -- the Hsync signal pulses once per horizontal line, just as the Vsync signal pulses once per frame.]