I happen to have a sub-collection of the general
type [
LINK] & I've actually got one of these -- an R.SECVNDA Emperor-captive -- but for
Valentinian I. Compare the lettering positioning and, as Shawn notes, the OP's
exergue is probably very crowded!

See
Warren Esty’s discussion on
his LRBC Officina Numbers page (scroll to table near end):
[LINK]