Try some of the Buick vendors like Classic Buicks, and a few more that I can't remember off hand - haven't had my first cup of coffee for the day yet. They may have some extra stock. Or, in other Buick forums like this one - Buickclub.org or the nailhead newsgroup. Someone should have an extra rocker or two laying around.
There are aftermarket rockers in the works. Tom Telesco developed and is doing the R&D before going "public" with them. When they do become available, this forum will be posted. They will be roller tipped with a true 1:6 ratio.
66' Gran Sport Skylark
Minot AFB, ND