Good to see that the chapter at Stevens Tech is doing pretty well. Unfortunately, it's been years since anyone has ever written a major history of Alpha Sigma Phi. The only two people on the National staff that might be able to help you out in obtaining more info about Alpha Kappa Pi other than what's already available would be our Grand Historian, Bob Kutz and our current Grand Marshal, Scott Grissom (an alum from my chapter). If I had the time (and the money) to spend a few days rooting through the archives in Indianapolis, I'd be in hog heaven!
Also check with the guys over at Alpha Rho chapter at NJIT; they were the original Alpha chapter of Alpha Kappa Pi. Hope this helps.