I don't think the automatics came with a 215 pump. I have a 1994 6bta but swapped in a 913 pump and DDPIII injectors so yes, you can swap out the pump and injectors for ones that flow more fuel, burn cleaner, and run smoother. I too have been told the 1994 pistons are slightly inferior but i don't remember why. I'm pretty tough on my truck and i don't suspect you'd have issues with the pistons under moderate power modifications.
If you want high performance pistons i think you'd be looking at ceramic coating. Swapping to a 215 pump can provide a significant increase in power. If you choose to upgrade injectors, i would go ahead and step into something bigger than 215s.