Stock? Hi Pressure? Hi Volume?

Building a 340 for my '75 duster, strictly for street use...before I had a stock pump with a hi pressure spring installed
I know you lose HP with the high volume...
Do I really need anything but the stock pump?
She wont see anymore than 6500 RPM and then not very often...
Also going to run a 8 qrt Moroso pan...anyone have one of these installed? I was wondering about the ground clearance? cant be much worse than the header clearance