How high do you plan to rev it? A rule of thumb is to allow about 10 psi for every 1000 RPM you plan to twist it.
If you are using a hydraulic cam and the rod bearing clearances are less than 0.0250" I'm guessing the stock pump will supply enough lube.
But Melling and TRW make inexpensive HiPo pumps so I'd say its cheap insurance with little downside, except maybe a smidge of horsepower loss and more stress on the distributor/pump drive.
