I installed a variable-flow model - it doesn't use a pressure switch, and runs at different speeds depending on how much you open a faucet...fairly quiet, as well, depending on how well you insulate the mounts...
Several Mfg's make these variable-flow models...I got ours from West Marine, it's their house brand, but is probably made by one of the major
12 volt water pump mfg'ers, Jamsco, Sur-flo, etc...
The one problem I've had with 'rebuilding' older pumps, is with the electric motor itself - sure you get the wearable pump parts with the rebuild kit - but the motors do wear out as well; bushings, commutators, and carbon brushes - and by the time you have to invest in a complete motor, along with the rebuild kit, you might as well purchase a whole new pump to update your system...IMHO