I used to toy with the idea of 113mm mags in an STI for a IDPA CCP gun but never did follow through with it. After I got a C2 I fell in love with the grip size and magwell and just decided to run it in ESP. That being said, I believe it is possible to make it work. Worst case scenario is you ruin the original grip and then reward yourself with an expensive but awesome SVI grip.
……or add up the cost of all the parts, finishing, your time/labor and then compare it to a factory SVI build. Another member of this forum did this and ended up ordering from SVI.