I'm led to believe that the WRX 2.5 block and STI 2.5 block only differ by having different pistons (rods, crank etc are allegedly the same).

Firstly, does anyone know if this is true?

If yes, anyone know who sells WRX short motors for a good price? I'd be replacing the pistons anyway, so not too fussed about them being STI or WRX.