Bigger fuel pump, the lph rating is determined by the estimated hp of the engine. It needs to supply enough fuel at the desired pressure but you don't want to push more than the return line to the tank can handle. There are some online calculators that can give you an idea of volume and pressure for your engine's needs.
Adjustable fuel pressure regulator.
BBC injectors. Some guys have run sbc injectors at very high pressure but since a 383 can make big block power you might as well run bbc injectors.
Bigger throttle body. You can use a modified sbc tb, usually bored to 46 mm, or adapt a bbc throttle body that has the 2'' throttle plates. Again, it depends on your estimated hp.
Intake manifold. The Edelbrock 3704 can be machined to match the size of the throttle body in most cases. I've read they can be bored to 2" but the shop that did mine would only guarantee their work to 46mm. They were concerned about going through the port wall if they went beyond that.
Custom chip for the ecm. No way the stock prom is going to handle a 383. Mail order chips are a possibility but it usually requires a few attempts and information supplied to the tuner via data logging. There are still shops that do custom dyno tuning for these old systems but they're getting scarce. If your budget is fat, just get a FAST Ez-Efi system and let it's onboard computer do all the tuning.
I've probably forgotten a few things but I think that's most of it. Other things like upgraded ignition parts, free flowing exhaust, and a modified air cleaner will also help you get the most out of the extra cubic inches.
