Get one with a center bore larger than 73.1mm. I think that's what it is for a datsun.
I ordered mine from ebay, they were two piece and haven't had any trouble with them yet.
Long nose r200 CLSD's are only in the z31 300zx turbos from 87-89. They will run you about $800-1000 depending on where you get it, or if you get lucky you can find it in a junkyard.
For that price I would put a little extra down and get the OS giken. What are you using this for? if it's mostly drag and rarely a street car I'd say just weld it.
I bought a car is very similar condition, basically giant rust holes everywhere and it was rusting in half. It was an 81 auto though with a blown head gasket. I paid $600 for it. And I made about double that parting it out.
First, you had it right, the more negative, farther away from the suspension the wheel lip will be. Second. were are you going to find a 255 tire for 16" rims. Lastly, the Rota group buy has the perfect sizes for ZG flares.
Of course it sucks looking for a z there. I left SoCal and had a hard time finding anything here in fl. That's why I found my 240 sitting in phoenix with coilovers and a solid body with a swapped l28 and triples for $2500 no interior but that was already the plan, needs paint which is fine since I want a custom color. Needs wheels and flares and then id call it good. And that's still less than what I would have spent on a rusty running car here in fl. Its sitting in my uncles in his shed out back to protect it from the dust storms till I finish school.
Lol an L28et is a wow factor. When you smoke some SR's with a straight 6 single cam and they ask you what it is, you tell them its a 30yr old engine.
You should be able to find a swapped Z for that price, but don't expect it to look pretty.
Keep it, fly to Socal or arizona to get a cheap rust free runner, use the money that you probably would have dumped into rust repair for a car in your area to make the runner look nice. Then decide whats more fun.
The best way would be to cut the roof off the non sunroof. But if your friends 240z is salvagable and he's trying to sell it then cutting the roof would basically turn to scrap.