Welcome to Hotrodders.com Glad to have you with us
What are you wanting to do? I know you said up-grade it, but that's wide open. Specifically what are you looking for. And what do you have for rear gears, tire size, what trans. you'll need to know all of this to put together a combination of parts/equipment that complement & work with each other.
IMO you should either get a beater to use as a DD until the camaro is finished, or get another 350 & build it in the garage then drop it in when complete.
Best of luck to you
Are you in the service? If so, I'd like to say Thank You!