So, I found an input shaft. Right there on PATC's website too. Just had to look for it a little. They have two choices, besides the $534 300M steel shaft. One is the factory 4L65E shaft at $59. It's heat treated from the factory and is stronger than the OE 700R4 piece. Then they have the 4L65E shaft that has been put through an additional hardening process for even higher torque capacity(580ftlbs). At $89, it's a pretty decent value. This saves me from having to reuse the factory input shaft with the Smart Tech drum.
Wow, The internet is such an awesome thing. 13 years ago when I tried to work on my own trans, there was almost no information available. There were books but unless you know where to look, it's hard to find good publications like ATSG offers. In 1999, when I first visited the idea of building a beefy 700R4, a local trans shop told me there was no way to beef up a 700R4 and that I should just go with a TH350 or 400. Glad I didn't take his advice.
Today, armed with the understanding that I have developed from alot of hours of research, I feel very confident in repairing this transmission.