A Hiscox case will fit harder-to-fit horns like a transitional Conn with split bell keys and a larger than normal bell. It will also fit a 10M or similar horn with opposite side bell keys. The only common vintage horns that I have found that will NOT fit in a Hiscox are Buescher 400’s because the bell comes out farther from the body than other saxophones. If you have a Buescher 400, pretty much your only option seems to be the Pro-tec XL alto or tenor case.
The reasons to buy a Hiscox are that it is the strongest case on the market, as well as the best insulated against temperature changes, and also the lightest for travel or shipping. But honestly, I wish Hiscox would add much better internal foam for protecting the instrument from drops and in shipping. The super-hard internal foam can actually damage the saxophone in shipping or if you drop the case, so I recommend that you at least add some softer foam around your sax inside a Hiscox. Or look at the BAM cases, as the Softpack and Trekking also fit many vintage horns, but have softer internal foam.
These Artist cases are black with silver interior, or add $50 for an ivory-colored case.