Mike,
Sorry for the slow reply. I have not been on the board lately.
I used 1 3/4" G10 with 1/4" wall thickness. McMaster-Carr # 86555K474
I opted for this because;
1, The outside diameter matched that of my shaft log so the rubber tube that connects them seals well.
2, the cutlass bearing (I believe I used a Blackfish) pressed into the I.D. tight enough where no mechanical fasteners or retainers were needed.
I hope this helps, your probably done with the job by now.
Mike
C227