Well if your measurements are accurate, that .060 won't be enough to solve the issue.
Was that a measurement from the head (or top of an existing shim) to the bottom of the retainer? In other words, the height of the spring only, not the thickness of the retainer
Barry's recommendation was based on a 1.80 installed height being "too loose" if you were at 1.90 or 2.00, it would make the starting point even worse, requiring more shim or even different keepers to gain more, or new springs.
I hate to delay racing, but it's pretty rough on parts when the valve train is uncontrolled. May want to consider getting an accurate installed height to accurately close up the space the spring sits in.
If you did go with .050 keepers and your .060 shim, that would be .110 total and worth about 45 lbs seat pressure. Depending where your height is now, that could do it on the cheap