8MM retainers/locks on 5/16 valves: OK or not OK?

the top of valve stem groove to the top of stem dimention is .100" as close as I can measure. AFAIK they are "std" height retainers. I do have some old 5/16 lash caps I found the other day but the depth inside is great enough that they do not set all the way down flush on the valve stem (if that is an issue) & I do have a contact problem as the roller (on base circle) is too close to the ex side of the valve tip (sweep seems OK tho).