i would imagine a 1st gen s10 blazer tank and sending unit could work with your truck. There is mine in my 1st gen s10 everything works great. As for fuel cells i dont know there.
If you want to run a cell all you have to do is make a ring to hold down the stock pump and shorten the pick up tube on the stock unit. bad pick in my profile.
I just picked up a Summit fuel cell, its 16 gallon with a GM sending unit. So that should hook right up with your setup, and its only $170 with the sender.