Strictly drag, but it needs to be street legal. I'm definitely planning on exhaust first off- the stock exhaust system is awful from what I can tell. Another thing I want to make sure is to keep it's reliability. I don't want to end up pushing any boundaries with reliability that are drastic. Thanks for the writeup, I'll keep it in my notes for this project. The car I'm looking in to has bad brake pads, but I'm replacing the braking system with performance-grade materials regardless.
My extremely loose and rough HP estimation would be about, eh, 250-300(max) HP at first. After that I'll deal with the new fuel lines and forged pistons that the extra power will require. Even then, I'm probably going to not hit 340-350 for a very long time considering it could be pretty rough to the stock block. Another thing I want to look in to is the transmission. A 280zx with automatic transmission will make up for power losses through brake-torque launching as well as a shift kit (hell, I may even be able to shift manually considering they're 3 speed), but I need to modify it for it to become viable/reliable.
Once I get enough sufficient research down I'll make a thread for the project, post the setup, and see if people will troubleshoot it for me. I'm aiming for initially doing modification to the L28ET that will be taken one step at a time, with a gap of time in between, so I can really get a feel for what each is doing, as well as re cooperate resources.