Very odd configuration.
A 38'x38" neo angle may work somewhat there.
Doing a remod on a foreclosed home where the previous owner removed the shower (in haste) before I purchased it.
I cannot seem to find a shower enclosure that will fit..
I've seen several company's round front (curved-glass) shower units. Can't think of the brand names now, but both Lowes and HD carry a version. You should be able to find the exact replacement if it isn't too old.
Important note - I'm not a pro
Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014
Maax has at least one, in their various lines. They are a manufacturer, so look on their web site.