I'm in the process of finishing up my Sniper EFI install on my 86 stock 305. To answer your question, I think this setup would be a good and affordable option for the fuel tank/pump:
• This in-tank fuel pump module is a high-pressure unit that flows 255 liters per hour (LPH) and is capable of supporting electronic fuel injection (EFI) engines producing up to 550 horsepower • A pre-calibrated fuel-level sending unit designed to work with the factory fuel gauge for this...
www.holley.com
According to what I've read, it just requires a little bending of the lines to get it to fit the El Camino 22 gallon tank. It's designed for the Monte Carlo tanks, which have a flat top, whereas our El Camino tanks have a bump on top.
Unfortunately for me, I used the external pump that comes with the Sniper Master Kit. After less than 100 miles of driving, the pump is already making terrible screeching noises. It freaks me out that it's going to die at any moment.
I can't report that I'm satisfied with the Sniper just yet. Besides the fuel pump problem, I've also had a terrible time with tuning. Understand that my stock 305 is a bit on the mild side for a 4bbl Sniper, and that I live at very high altitude (9,200 feet). But in my situation, the Sniper is not "self-tuning" at all. In fact, the more it tries to self-tune, the worse the cruck runs. Right now, I'm trying to put together a drivable base tune so that I can get out on the street and generate a log file to send to the tuning experts over on the Holley Sniper forum. I'm hoping they can look at my system and help me figure out what's wrong.