I'm a big fan of reconditioning and reusing original parts when possible. Have you tried salvaging the fittings? I saved the banjo fittings on my Jag E-type a few years ago, which were similarly corroded.
I dipped the parts in a 50/50 distilled water/muriatic acid solution for 30 min. Fwiw, muriatic acid is really nasty stuff. It'll burn your skin in a hurry. So wear gloves, long sleeves and good eye protection. Do not breath the fumes. I'd recommend a well-ventilated area or outside (definitely not in a closed garage). And don't forget to add acid to water, NOT water to acid.
Check on the fittings every 10 min or so. By the end of 30 min, the acid should have dissolved the rust leaving only clean steel. At that point, you can decide if pitting is too severe for the fitting to be saved. In my case, the fittings could be salvaged. I lightly sanded the gasket/crush washer mating surfaces with 220g then 320g wet/dry sandpaper on a flat surface (I used our kitchen countertop . . . my wife was thrilled). Then treated the fittings to prevent future corrosion.
For anti-rust treatment, I've had decent luck with Ospho (main ingredient is phosphoric acid) rust treatment as it leaves the surface with a rust resistant phosphate coating. If you want the finish to look "pretty", use a brass wire wheel mounted in grinder and buff until you have a nice shine. You can then clear coat the fitting. Or skip the wire wheel, and just leave the phosphate coated surface with some oil rubbed in. I did the latter and it's been 2 years since treatment with no further corrosion, and I live in FL. Then again, the car lives indoors and doesn't see wet roads so YMMV.
Alternatively, you can zinc plate them. There are plenty of vids on Youtube showing simple zinc plating at home on the cheap. I have a constant current power source, but I've heard of plenty of people using car battery chargers and car batteries for plating with reasonable results. I zinc plate seemingly endless amounts of Lobo bolts, nuts, washers, brackets etc in my garage so my own setup is pricier, and too expensive if you're just looking to protect some banjo fittings.