Most jet pumps will run fine at 60 psi when in good shape. Be sure you are incorporating the lift from the surface of the lake to the top of your house into your math. Also the pressure switch should be plumbed right at the pump. A larger tank allows more flow before the pump comes in, and will lower the number of cycles your pump needs to run but has no effect on the pumps ability to do the work. If you need more lift and higher pressure a submersible pump right in the lake is a great upgrade and does not require priming if you ever run the pump dry.