Just as slow as before mods..

Looks like it might be square sided. It might be a fuel cell, and it might have an in-tank pump.
Assuming the leak is in the lines, you could keep that. Run a short flexible line to a copy hardline, then to a regulator, then filter and to carb. If you must use hose for distance, then something like AN (Army-Navy spec) is the best choice, although expensive and a PIA to work with.

On the other hand, if the only way to solve the leak is to drop the tank, then going stock may be the way to go.
Because:
1. Factory or factory copies fit and function without a lot of custom work. Steel or stainless hard line is better than long hoses.
- Aftermarket copies are not always as good a fit as the orignals but for fuel tank and hard lines the only regular issues reported are the fuel sender accuracy and the lock rings. Good lock rings are available so, no problem there.
2. There's no need for electric pump with a carb. But it puts a load on the electrical system these cars were not designed for.

A Holley 110 mechanical pump or the Carter stock type mechnical pump will keep the carb filled and not need a regulator. One less thing to go wrong.
One issue with '73 may be the vapor capture. You may want to go with an earlier tank.. Others here can advise with regard to that, if you go that route.

If you go this route, the fuel cell and electric pump can be sold. Cells are required for some types of racing.