Hi Tom, It seems people are a little confused with your question and think you have the upper inlet off of a phase one 172 which has a cable operated throttle.
Your old '53 plate 172 would have been the mark 2-phase 2 with DBW throttle body so will be the same upper and lower inlet manifolds as the ones for the 182.
As the lower inlet already has RS stamped on it then the chances are it is off a 182 anyway.
From what I understand, it is the earlier lower inlets that gain most from porting and matching. The latter RS stamped ones were better made so only need matching.
Once the inlets are matched then it won't matter whether they were off your old 172 or your new 182, they will give the same small but nether the less worthwhile gains.
Hope that helps clear things up.