That would be great if you were to get the "older" style caliper to work in the "newer" caliper bracket. I have never tried it myself, the info I have that they are incompatible came from North Ursalia. IIRC he said the pin spacing was different. I know the pads are also different but thats again solved with the bracket. Meaning you definitely need new pads for the new bracket.
I think the reason that have run into this is that most of the people who have done it have had the newer style calipers already.
My basic point being that I wasn't aware new calipers were needed. Similarly to how the USDM GC 2.5RS' front calipers are the same as the USDM GD WRXs' are, only the WRX adopts new, bigger brackets to accomodate ~1" larger rotors, I have always been told that the rear calipers are the same among the three models, as well (GC Impreza, GD Impreza and Legacy H6).
This is correct accept the GC Imprezas got the "newer" style calipers in mid 98 MY. All the earlier Imprezas and the BC/F and BD/G Legacys have the "older" style rear caliper
Let us know how it goes ciper.
I actually pulled the dust shield off with nothing more than gloved hands. Then cleaned away the spot welds with a grinder.