Found the problem and it's not in the valvebody. Turns out my trans has a 18 spline input, and I ordered a 27 spline converter (which it's supposed to have). So either someone used early parts to rebuild this trans in the past, or I have an early built car using leftover '67 parts. I also noticed when installing the shift kit that it was missing some elements in the valvebody that were listed as being 68 and later.
So some quick searching has shown that there are not many options for 18 spline converters. Tflite patty on ebay has a high stall reman, and I would also need his spacer to get the small snout centered in my crank.
I could also flush my old converter, it shows almost no wear on the snout.
Last option is try and convert to the more common 27 spline. I'm not sure how much parts that would require.