...your PO is a 2500 or a 8500. If yours were a 8500, then you already have that novelty on your wrist and I may suggest getting the 1861 Speedmaster just so you will have an Omega from an older time also. But as your PO is a 2500, I think it wouldn't hurt for you to own a newer Omega model in any case.
It's a tough call. But fitness to wearing habit and value for money rank higher for me than historical connection. If a watch checks all those boxes then it's even better.
One thing to keep in mind. Newer Omega chronographs are likely going to get the 9300 movement. By buying the 1861 now, your future Omega chronographs (e.g. Planet Ocean Chronograph or De Ville Chronograph) will have the 9300 in it anyway and you will end up with different movements for all these watches and zero redundancy. I hope I am not over-analyzing this. Good luck!
Ruckdee