Speedy Jim wrote:
M Q wrote:

....


For your present 70Ft well, you likely have a 1/2 HP (maybe 3/4 HP)
pump.
Going down to 250/275 Ft, you will need a 1 1/2 HP, maybe 2 HP.

I don't agree here. There should be no additional head for a
deeper pump, as the water table will be at the same depth.

SNIP

Yes, you're correct, of course.
That's if the water table is the same and he is merely
placing the pump under a 200 Ft head of water in the well.

But the intake and discharge _from the pump_ will be at the lower level
so there is additional head -- the length of pipe from the former
elevation to the new.

More reason to get local advice before jumping in.