stock rocker spacing.

O.k. Yes I assumed he was running a hydraulic cam. Maybe we should ask that question first. If it's a solid cam yeah you will be able to move the rockers side to side a bit since there is no preload. For the side to side movement. .090 Is probably too much play for the solid rockers. They make shims for the solid though. If your running a solid cam with adjustable rockers there are supposed to be spacers in between the rockers. Alot of times they are sold used with out them because they were lost or misplaced.

If it's a hydraulic cam.....There may be a little side to side play, I know all the stock rockers I have ran had some play side to side.(not sure if it was .090 though) But!!! You should not be able to move the rockers side to side easily just like I said before. I know the issue is the the rocker arm spacing and side to side movement. If your rockers have the right preload they should not slide on the shaft easily to begin with. If the spacing is a concern I do believe you can use the same shims for the solid cam to fix that issue. They make shims in varying widths or you could just find the dimensions of the stock shims and make your own. I could probably post the dimensions if you need them. I have stock shims in the garage that I could measure.

personally I think the correct preload or gap on the rockers is more of a concern. You could possibly throw a pushrod and there is a wear issue on both the solid and hydraulic if it's not set up right.