Congratulations.
I can recommend JZ Machtech for any service work. Jonas, Steve and David know these cars intimately, and have worked on them since they were contemporary, and look after several of the best RSs.
It is worth enjoying the car as it is, but gradually getting the parts together for a time in the future when you want to give it a more thorough restoration. Although a full strip down and rebuild is expensive, often it is far better than continually fiddling around the edges.
IMO best money you can spend now would be to get JZ to check it over, tune the MFI on their dyno, set up the geometry and brakes. They will also fit a discreet immobiliser. Ask Steve about the engine. At rebuild, it may be worth 'back-dating' it to '73 spec, with new crankcases. Don't know if you can re-stamp the original engine number. You couldn't disguise its history, but you could get as close as possible to ex-factory spec., which is what most people want.
Nice project, a genuine piece of Porsche history, and yes, the RS really is a remarkable little car.