I used a 3/8 unit but I had to adjust the float level and used a new tank. honestly I didn't try it without adjusting it though. and my adjustment is off to my liking.
I added 4 gallons of water to a new 16 gallon tank with sender and checked the gauge and adjust to exactly 1/4 tank. I should have made it 1/8 tank as now it reads full for a long period then goes down rapidly when it hits E then it is empty, no reserve. Knowing that I never let it never go below 1/2 tank. I do not know of a perfectly set sender out the box.
I think the max you can go in the tank before it runs out the sender hole (lowest point) is 7 gallons. this is with a 67 cuda tank which is the same tank for most a-bodies... easy math to adjust
