Keep it!
Of all the pistols which are keepers its the FWB 65's and 80's which are top of the list, the design is superb and they are very different to any other match pistol. If there is one pistol that you should keep its this one and you will at some time regret selling it. They are collectable now as well as a good shooting pistol, in years to come they will be the valued collectable.
Yes you should get a modern PCP, you will probably shoot better with a modern PCP, mostly because the ballance and ergonomics and the lock time is faster but they will not be any more accurate. The amount you'll get for the FWB is 20 to 30% of what it will cost you to get a Morini, keep it and save a bit harder to get a Morini.
I still have my 65 bought new in 1972 and of all my guns its the one that would never go, sell it and some day you will regret it.
Good Shooting
Robin
Walther KK500 Alutec expert special - Barnard .223 "wilde" in a Walther KK500 Alutec stock, mmm...tasty!! - Keppeler 6 mmBR with Walther grip and wood! I may be a Walther-phile?