says free length inner 1 7/16" ( 36.312 mm)
outer free 1 3/4" ( 44.45 mm).
2" outer (2.03" outer , 1.62" inner ), 1 5/8 inner type was fitted to very early A65 62 -65, these would fit with the early valve / collet arrangement, which changed to a smaller collared collet in later years
SRM supply outer 41.75, inner 39.87 ( triumph type ) ,which is what I now have fitted,
head part numbers change over the years, I dont know if mixing valve springs from early and late will work on any particular head, .I have no experience with the 62 -65 heads/ valves, I dunno if mix n match is OK or not.
Given that the springs got shorter over the years but rockers stay the same I reckon BSA thickened the casting around the valve spring pockets, maybe to allow bigger ports. i know you cant mix n match early collets with late valve spring top keepers and visa versa.