The 1.5 rangefinder/diopter conversion can be found on post war conversions but I have never seen it on a I to II prewar.
On I to III it was normal and part of the package.
There are a few things for the OP to ponder.
If he is intent on selling then sentiment aside (which I do understand), I'd expect he'd get noticeably more splitting lens from camera, indeed I reckon the lens (if good) is really where the money is.
The value of conversions, unless something really special, is now roughly the same value as what model they are now. Apologies for the English but I hope you get the gist.
It is possible that the lens was converted at the same time as the camera and that originally it was all a Leica I with fixed Hektor. Possible but then they only made 1300 or so, therefore unlikely.
'Early lenses have no serial number' This applies to Elmars and earlier, think it may also apply to Hektors.
If the lens has got a serial number on it then being a conversion is unlikely.
Vulcanite. It is a shame that it is split. I've seen some excellent vulcanite repairs using black setting wax etc. If you re-cover the camera it will lose originality and therefore value...but the value is lost already because the vulcanite is split. As far as I am aware the last person to do real vulcanite re-covering has retired. Some choice!
If selling I'd sell in original state which would appeal more to collectors.
The shutter guard is not original.
Apologies for the long post, we are in Tier 4 lockdown and time is on my hands!
