What you originally wanted to do can be done with a Glendale bridge. They’re not cheap, but probably cheaper than the Callaham you were going to use.
I went a different way with mine - the body was drilled with 4 holes for an ashtray bridge, but I initially put a Gotoh 6-saddle modern conversion bridge on it (I can’t remember my reasoning…). I was curious about the vintage style after a while, so I swapped one on and have never wanted to go back.
What you originally wanted to do can be done with a Glendale bridge. They’re not cheap, but probably cheaper than the Callaham you were going to use.
I went a different way with mine - the body was drilled with 4 holes for an ashtray bridge, but I initially put a Gotoh 6-saddle modern conversion bridge on it (I can’t remember my reasoning…). I was curious about the vintage style after a while, so I swapped one on and have never wanted to go back.