All fixed. I figured there had to be a blockage somewhere so I went right to the low side line. I pulled the R134 valve and there was gunk behind it, blocking the flow of refrigerant into the system. I sucked the system down good, recharged, and voila! Cold air flows.

I'm thinking there was some junk in there left over from the restoration process. That would explain the venting of the refrigerant and the gunk I found behind the valve. There was probably a blockage at some point that increased the pressure and tripped the high pressure blow off valve.

Thanks for all the input, Guys! See you at Carlisle!