Any lash caps that I have dealt with have valves with the ends machined smaller so the lash cap can fit over the stem..I don't think they have them to just pop on over the standard valve tip..As for modifying your valvetrain geometry to move the contact point away from the center of the valve I don't think its a good idea..You want the pattern as centered and as narrow as possible.

 

according to william mathis roller should contact stem tip 0.025-0.035" from center on stud side.

minimal tip roller travel is desired; everybody seems to agree..

mathis likes geometry which accelerates valve when first opens and minimizes acceleration at valve full open.

not all 1.6 rockers have same dimensions..adding to the geometry fun...

lash caps are available in press on and slip on; i must measure stems to see if one would fit. i will inspect all stems closely before making decision.

lash caps used in many racing applications. lash caps are available w/ lash locks for those who like to float their valves. specifications are sparse. many caps don't spec type of valve. one cap specs must be used w/ titanium valves; don't know why???