I built a fuel cell out of 16ga and used the stock sending unit. Total cell cost me less than $75. Coated the inside with Por-15. Never had any problems at all out of it. All the stock gauge and console info worked great.
Here's a reason why you shouldn't drag your gas tank. I would rather it look bad in the bed that this to happen.
http://www.streetsourcemag.com/Forum/topic.aspx?method=reply&topic_id=89507&forum_id=14&forum_title=&M=False&S=True