Very nice! Thanks for posting those!
I've been bidding on the Tikkakoski barrels that appear on GB for some time now (the longer ones - ~4 3/4", IIRC). They look to me to be in about perfect balance with the rest of the pistol. Something like the 1900 series, but with the thicker 9mm barrel.
Just out of curiousity, are you sure it's an after-war add-on by your dad?? Many Lugers were fitted with Tikkakoski barrels by the Fins...