Rosewood,
Not exactly sure what you are after but when I tried to match my existing 25 year old pipes to a new filter the local Pirtek manager sorted me out using his personal knowledge, i.e. he had an unpublished list of bits for dealing with awkward interfaces.
Filters with 1/4" BSP female tappings are readily available if that's what you need, as are reducing bushes to get down from 3/8" BSP or even 1/2" if that's what you need. as has been said ASAP or online filters are pretty good and for reducing bushes BES always have good a selection.