Early last month I replaced the anchor material on P1 of Sixish. I used 7mm cord and combined the three pins with a half sized tri-cam equalized to a master point with a pair of aluminum rap rings.
I'll guess that for descending you intended to reach this P1 anchor by rappelling from the GT ledge. Not completely obvious how to get from the top of P3 of Sixish down to the GT ledge (since the top of Sixish P3 is not such an inviting spot to rappel from).
Anyway I note that once on the GT ledge near the top of P2 of Sixish, it is straightforward to walk horizontally southwest on the GT ledge to the Kamasutra rappel anchor, with bolts and chains. From there it's straightforward to make two single-rope rappels to the ground. (I'm not recommending
this approach for descending from top of Sixish, only suggesting that it's better than using the popular + narrow Sixish P1 anchor).
Of course this does include rappelling down a possible ascent route, but:
(a) the Kamasutra bolt-and-chain anchors were installed by the Mohonk Preserve, pretty obviously intended for rappeling;
(b) Kamasutra P2 is rarely climbed upward, and Kamasutra P1 virtually never.
And of course it's very straightforward to just walk off from the top of Sixish with no rappeling at all -- first find a way up toward the top of the ridge, then follow the ridge trail roughly southwest to one of the descent routes near the Uberfall and down-climb to the Undercliff carriage road. (or if cannot handle class 4 or low class 5 down-climbing, can continue following the trail roughly southwest until it comes to a long but easy scramble down to hit the carriage road just a bit east from the "practice rock".