Alpo is wrong about the New Service. It is on a large .45 frame, not the .41 frame of the OP and Python.
If you want a six-inch bbl. for certain, get the OP. The frame better suits that longer barrel. The Police Positive Special was more of a service gun that could be concealed. Its virtue was handiness. With a four-inch barrel, it made a lot of sense. The five inch was pushing things, and six is just too long, I think.
I beieve I'd try to get one made in the 1950's or later, as the metallurgy is better than the old guns. Colt advised having the small frame .38's inspected after firing 3,000 rounds of Plus P ammo, to be sure the frames hadn't stretched. No such issue with the larger Official Police.
The OP has a grip that'll probably feel very good in your hand. i think Frank Pachmayr had this in mind when designing his Presentation grip, which is sort of like a larger OP grip in a way. It has the same oval feel.
Be aware that the gun may not shoot to the sights, and you'll need a KNOWLEDGEABLE gunsmith familiar with older Colts to turn the barrel very slightly to get the barrel centered with the sight groove in the frame. Askins had to re-sight almost all of the Colts he bought for the USBP while their chief firearms instructor. You may get lucky. I once owned a .45 New Service made in the mid-1930's that was dead accurate; shot right to the sights. But don't count on it.
Keep us posted. I urgently suggest that you locate and buy copies of, "The Handgun", by Geoffrey Boothroyd and Haven and Belden's, "A History of the Colt Revolver, 1836-1940." And get Elmer Keith's, "Sixguns", preferably the updated 1961 edition. Do you know the difference between the Police Positive and the PP Special? You want the latter, in .38 Special. To confuse matters, the final edition of the PPS reverted to just the PP name. It came with a bbl. tht has an underlug like on many S&W or Ruger guns. I don't know why my typing turned black.
