30 year old well system- complete replacement- pump, tank, etc.-nuts?

[LLigetfa]

Or, you could just use galv. tank like me.

Sorry, I couldn't resist.

Ja, those generally have additional drawdown below cut-in so long as you don't supercharge them with air. My Wellmate composite hydro-pneumatic tank uses a AVC that supercharges the tank to maximize drawdown. When the drawdown is exhausted, the air that's left will blast a glass right out of your hand.

 

[Texas Wellman]

You still supercharge them, not just all the way. An 82 gallon galv. tank has a natural 8 gallon draw down (30-50). When you supercharge it to about 1/2 water to air it has about a 20-25 gallon draw down. If the pump were to go out and the pressure was at 31.5 psi you would still be able to draw ~10 gallons out of the tank before you either ran out of air pressure or ran out of water. You would have to experiment to find the right mix.

Some of our wells are naturally gassy so they are always supercharged (with air releases). Pulled some 30 year old pumps out of those wells.