Here is what I have found out. I bought this summit brand harmonic dampner and just had it installed.
<img src="http://static.summitracing.com/global/images/prod/large/sum-b64269_w.jpg">
I wanted a nice pointer to go with it but when I called to summit, they said that there was no pointer that would fit. I took this to mean that because the balancer was 6.6 inches as compared to the 6.2 inches stock, that the balancer would physically touch the pointer. I called Fordz Racing and asked about the pointer I linked to above and whether it would fit a 6.6 inch balancer. The answer was "no problem." I called back summit to find out why they say no and Fordz says yes. The tech read through a tech memo on his computer and said that when they say that the balancer does not fit, they are talking about the timing points not matching up if you use the 50 oz counterweight. This situation results in the timing marks etched on the balancer not lining up with the pointer. However, if you use the 28 oz counterweight, then the timing points line up as they should.
As for 10 o'clock/11 o'clock, this does not refer to where the pointer points on the balancer but the location of the key on the crankshaft snout.