Welcome to Hybridz...the one stop shop for Datsun Lunacy on the web! LOL!
I love your cars, the RB25 S13 - Two big thumbs up nice clean install and I bet that car goes down the road VERY nicely! Beautiful conversion. The car looks great even with the 14" 6spoke ZX wheels too.
Your ZX is a great machine too. Pity it was not painted white inside the engine compartment when the car was repainted. Bras are useless on cars and women! I had one on my ZX when I bought 6 years ago and it ruined the paint underneath as well. I ended up repainting my hood and front fenders as well. You did a very decent job on the hood repair - excellent.
As an aside there is a thread on Carbon Fiber Hoods for the ZX using the ZXT NACA duct if you go under "Vendor's Forum" its a thread we have signed up on and JohnC is the one getting it done for us - hopefully soon. So I encourage you to sign up, if you want a CF hood.
To answer your questions, you can turbocharge your NA ZX and many people have you will be boost limited but trust me at 8psi it will be on fire!
The NA L28 has the same rods, bearings and crank as the L28ET
The NA B Series tranny will be plenty strong to 400ish hp, depending on your driving style, clutch dumps, burn-outs etc. I actually removed my B-W 5speed and replaced it with a NA 5 speed tranny and my car had an easy 250hp. I'm rebuilding the motor now and looking for much more hp and will still run the same tranny - we'll see how it holds up. There is a great thread about adapting the Z32 Tranny to the L series motor by Garrett - so you may want to do some reading there.
Hope that helps.
BTW...I'm partial to ZX cars especially the white ones....wink:
Regards - Yasin