fresh 904 rebuild, not shifting at all

Sorry I was typing when you were writing your last response and see you answered the question about the pickup.

As for a gasket installed wrong. The only 2 gaskets a torqueflite has are the pump gasket and the extension housing gasket. None on the valve body. That's a GM thing.

I suppose it's possible to install a pump gasket wrong. If it was installed wrong that'd sure cause no oil pressure.