Yes it is possible to cut high armholes with gussets- we do it all the time for theatre. I doubt though if many "regular" tailors do. The low armhole and gusset could be that it was easier to alter the sleeve pattern to make it work rather than change both the body pattern (armhole) and the sleeve pattern too.
In terms of movement and sleeves you have to determine if you need forward reaching movement or raising your arms above the head movement. They require different manipulations.
Reaching forward requies a longer hindarm and that is usually accomplished with a sleeve that has a shallower sleeve cap height and is therefore wider in the upper arm as well. This can be done and doesn't have to look messy- I think it gets messy when the shoulders aren't fit properly, along with an excess of back width, and the extra length in the back of the sleeve all combined.
Reaching upwards requires more length at the front and front underarm area with little extra length added at the back. If done correctly this kind of a gusset is barely noticable when the arm is at rest. The width of the sleeve is not noticeably changed.
The expansion gussets were common in sporting jackets but a system of elastic cords and such, sounds like a contrivance to me. Why not use an inside lycra panel instead? It begs the question as to whether the jacket is actually for a sport or just to look like it.
I have my doubts about finding many regular tailors who would make these garments. Even the guy at London Lounge site seemed to have run into a roadblock suggesting his jacket have a half belt- well I think it would have been actually easier to construct if the jacket had a back waist seam and then a belt would have been appropriate.
It would be a lot of work for a tailor who isn't familiar with cutting the variety of those historical styles and perhaps doesn't have a source for references, and more expensive for the customer too.
reaching forward requires adjustments to the under sleeves that is where you add the gusset, separate or built in. like a jacket for somebody who is directing an orchestra.
If you want to reach up you need more length in the sleeve inseam. you would have to raise it, however this will cause to enlarge the muscle as the raising of the sleeve inseam will reduce the sleeve cap length meaning that the sleeve will no longer fit in the original armhole, so in order to put this amount back you would need to slash and open the sleeve thus increasing the muscle/ upper arm.
Edited by stefano, 20 December 2014 - 04:00 AM.