I agree on the AZ supply line. It removes the banjo bolt/fitting setup, and improves flow.
For the shim, I used a 10mm nut. (It works fine, and since it's just one thing, it's slightly less difficult to keep track of while you are doing this job. Also, it's about 5mm thick, slightly more if I had to guess.)
If you look at this oil system, any higher pressure at the pump is going to be lost as soon as the main galley is reached. (On my system, the oil filter and cooler is in the middle, but after those, the pressure at the engine is going to be released via the squirter nozzles.)
On the stock setup, the oil pressure will be lost at the stock oil cooler bypass. (Another place to shim if you are using that part still. IIRC, it opens up at 40psi, just like the stock oil pump spring, and you are basicy bypassing oil pressure to the cooler, and then dumping that cooled oil into the pan.)
My setup has no bypass oil cooler anymore. Is shimmed with a 10mm nut and two thin washers, so it's about completely closed off at the pump. (Start up cold oil pressure is very high.)
But when it's warmed up, I'm happy to see 10psi per 1000 rpm or slightly better. There are plenty of places for the oil in this motor to bleed pressure off into. (Squirter nozzles, main/rod bearings and cam saddles/caps.)