Why not make a chamber cast or measure the neck with a set of .001" increment gauge pins? Then you will know what the neck diameter is.
A RCBS trim die has a neck diameter that is .010" larger than a RCBS FL die.
The RCBS trim die would serve as a body die.
To size the neck you could use a Wilson hand die with a bushing that is exactly the size you want.
Other than that you could use a Lee collet neck sizer die or a lapped out conventional neck sizing die.