Always appreciate the sage advice I get here.  Dropped my tank last week to wire brush and "Rust Encapsulate" as much of the frame as I can get to.  It looks original but no build sheet.  I notice the tank is heavily scaled with rust on the top near the sides.  It has not gone all the way through but it is pretty rough.  Should I wirebrush the tank, use some rust converter and paint and put it back or replace it at this point? It has no leaks and the inside is pretty clean too.  Just not sure I need to spend $200 on a new one. Opinions?  I know you have them!

Depending on how bad the rust is would be the key. Most times if the rust flakes off in pieces that are what I would call chunky I would probably replace it. If you can take your finger nail or a screw driver and pick pieces off then I would replace. On my 72 I just did the wire brush and then painted with POR15 paint. Mine was just a very light powder rust so I wasnt really worried about it leaking. The good thing is that the tank isnt that hard to get down should it leak at a later point.
Just a word of caution, this is where the "while I'm at it" starts. Next thing you know you have replaced motor, trans, wheels, tires ect........  LOL   Be careful!
Best of luck,
Rodney

Rodney, I resonate with your "while I'm at it" syndrome.  That started 6 years ago with me "freshening up" the engine bay! Cars been off the road since. And it continues ...while the tank was down I removed the rear bumper hardware and taillight housings 'cause they were rusted.  Going to try and sandblast them but they are pretty pitted too.  (Car is from Canada) Thats why I was thinking of skimping on the tank.  However there are big, big flakes coming off with deep pits so I guess it's a new tank for me.  Anybody have any good sources?  Quanta was not the cheapest, actually Rock Auto is but it's not reproduction.  I'm never gonna be a NRCS guy anyway!  Your posts have inspired me to get off my butt hope to have this car on the road by spring!

In the case of the gas tank it is not hard to replace if it leaks.  So in my book it is something I would not replace until it leaked.  If you stop the rust and you will there is not damage and it should not get any worst in the next few years or even longer. 

If I wanted to get it a little thicker.  I may put a piece of fiberglass cloth on the spot I was concerned with or even some liquid rubber.  The kind you dip tools in.

You said it was on the top part of the tank Not a big issue in my book. More and better things to spend your money on.

If you start picking at the chunks of rust that's on there, it WILL start leaking. As has been said, if you're getting large pieces of what used to be galvanized steel flaking off, the tank really needs to be replaced. It's more of a safety issue than anything else. I tried fixing a SMALL pinhole leak in the tank of the '74 3 times before I finally gave up, and bought a new one.
Quanta is the only place I would recommend, regardless of going full resto or not. They're really not that bad, price-wise, for the quality of the tank. I put mine in way back in '99, and it still looks brand new, inside and out.
Another option would be a good used one, if you can find one.

Mario, since you have already done the hard part of getting everything removed....I'd put a new one back in. I know as I get older I hate thinking of doining it over at an even older age.

 Just a Word of caution, IF it did leak and there was any possibility of SPARKS, "FLAMES" look nice "on" the paint, but not under the paint. Do it once, do it right, save the headache.

My gas tank was leaking on to the exhaust pipes.  All I could think about was seeing all my hard work going up in a huge fireball!  So I replaced the tank and all the hoses.

If the tank does continue to rust inside, you will eventually get to replace the tank, your fuel pump and filter, rebuild the carb, replace all the rubber hoses in the fuel lines and blow out all the metal ones.  Gets expensive, I know from experience.  

Wow!  Since this is election season, I'll go with the majority, the "replace it"s have it.  If I wasn't worried about safety before, I am now!  But seriously folks, thanks for all the input!  Ebo, was up your way this weekend visiting my step daughter again, should have stayed, coming home to a hurricane!  Good luck to all in Sandy's way!