Just dont do it the old way with a bolt in a pipe and nothing else
My NEW Azusa kit is exactly that,a 5/8" bolt through the 3/16" upper and lower "tree's" and through a thick wall chunk of what appears to be DOM tubing.
My ArcticCat project was 1-1/2" tube that looked to be relieved for ball bearings,but as a devotee of overkill,I centered a chunk of .120 wall,1-1/4 DOM inside the neck,and tacked it in,then slid a chunk of .120wall 1" DOM inside that with bronze bushings and a 5/8 bolt. The bushings protrude just above the level of the 1-1/2,so my pivots rest on a full 1" surface and basically a 1" shaft.