Hey Michael, I thought id chime in on cams since I recently had Rebello Racing (in Antioch, CA) do a regrind on a stock 280z cam for me into their 63D cam. They did a great job, and offer a valvetrain setup consisting of reground cam, springs and lash pads for about $400, and I had them clean up my rocker arms too but i forgot the fee for that. I did send them a core cam though. I wouldnt recommend the 63D cam due to its longer duration and lift, but they have other 'streetable' options that would suit your needs. Compared to Schneider, I originally was going to spend $800+ on a cam, springs, retainers, rockers, lash pads and some lube. The reason i didnt go with Schneider was due to them not having lash pads at the moment, but im very happy with Rebello.
Also, Ive looked into the Arizona Z car 4bbl intake setup and I feel it could be better... Ive read reviews from users that 1st and 6th cylinders dont receive enough fuel so those two run leaner. I cant speak from personal experience on it though, I went with triple webers for my setup! Haha. If I were in your situation and wanted EFI, I would rather get a 280z/ZX intake manifold and run supra injectors from a Pallnet or other aftermarket fuel rail, and have a different throttle body run by megasquirt. Theres obviously more to it, but I hope that gets the idea across because im falling asleep as I write this, lol. Megasquirt is quite the learning curve though, but I hope this helps you decide upgrades for your Z!