Installing A Salvaged Flushometer Toilet

[Arcasta]

I am hoping to replace my current toilet with this salvaged 1930s Kohler toilet. My current toilet is a rear spud flushometer, but the salvaged Kohler toilet is a top spud. The water supply line is 21 ¼” above the floor. The toilet has a height of 15”. Unfortunately, with a top spud toilet, this allows almost no space for the vacuum breaker/flush pipe, and certainly not the required 6”. I was told by one plumber that the only option would be to open the wall and raise the water supply line. However, I am not willing to do this and damage the original tile. So my question is, is there a work around? Can the supply line be raised outside of the wall? Can the vacuum breaker loop/twist to get the 6” length? My bathroom’s rough-in is 13 ½” and the salvage yard claims the salvaged Kohler has an 8” rough in. In that case, could the vacuum breaker curve down as for a rear spud, and then back up to the top spud of the salvaged toilet? I’m willing to consider any options that don’t involve opening the tile. Thanks!