Cam, as you suggested, it is a 03/38 model making it an intermediate action.
The barrel, follower, spring and floorplate arrived here today, much to my delight. Here's the bbl:

As you can see it has a sporting front sight base and I suspect the muzzle was shortened slightly when it was fitted as it's about 25.5" long. The bore is lovely. Not shiney but zero pitting and very good. Even the bluing is pretty good. Here's a closer look at the tag and the military rear sight base:

The Turk floorplate, follower and spring also appeared.

They fitted perfectly......except for the floorplate.

It was too short by about 3mm.
It didn't really make a great deal of sense so I rang Harry again to chat with him about the problem.
That brought us to the real issue.
Here's a pic of the box mag/trigger guard from underneath:

Note the arrows.........provide any clues for those Mauser-knowledgeable readers?
If not I'll fill in the blanks.
The arrow on the left pointing to the hole by the front action screw is for a locking screw.
Turk mausers don't generally have lock screws.
That isn't a problem in itself but the right hand arrow seals it.
That edge sticking out into the box is the feed ramp.
Try using that box and rounds willl hang up in the mag.
Clearly the mag is from a Columbian carbine or the like.
After ironing this out with Harry through a convoluted question-&-answer session he said he'd send down a Turk box mag complete with matching floorplate.
The bottom line is I reckon I'll name this rifle Frank.......short for Frankenstein!!
So until the Turk mag arrives I guess I'll be waiting.