Agreed, this looks like it's been refaced, the plating of the table ends just at the window. It is not very open, 0.085 measured. but there is not the slightest indication of a shank extension. I haven't played it. The chamber size is really not affected (maybe 10 mil), which, given the size of this piece appears really negligible. And the work was done by a master but it might have been a very early science project.
That's indeed not really open. I also have to come back a bit on the shank extension: the tenor shanks of ML's are really short, but those of baritones seems to be longer. I found some pictures in a for sale ad on Reverb, see here:
Vintage Otto Link Master Link 3 for Baritone sax.Refaced and opened to a 90 by Erik Greiffenhagen of Mouthpiece GuysHe opened it to a 90, thinned the rails and added just a bit of rollover baffle to wake it up a bit more.It still plays very warm dark and vintage but with a bit more pop and a more...
The shank is longer than I thought, but yours has a completely different look and also angle. It also looks like a butt cut was done. So what might have happened is that the original shank broke off and that it was repaired and opened up.
Another very noticeable difference is the shape of the part where the ligature should slide in. On yours it's much smaller than on above piece. Also no identification numbers or letters at all, like in above one. So maybe Nick is right and is it a heavily modified Tone Master, or even worse, a fake.
If it's a modified TM you should see a ridge (or remainders if it was removed) on top of the mouthpiece, which TM's had to hold the ligature in place (like normal STM's also have, but a bit lower). Original TM's (and Four****'s) didn't have such a ridge, hence they used the slide under ligature.