Is there a drop-in replacement for 4275 + 4276 hinge?
Not exactly drop in replacements, this particular modified plate has no protrusions around the hinge, it's entirely flat.

I see two possible replacements:

44301 and 44302. However they "click" in angles of 22.5 degrees and have protrusions...

60478 in combination with 63868 (clip and bar connection) is freely rotating but ofcourse again protrusions...