A Question of Oil

I recently acquired an '85 N/A 300ZX coupe. Naturally, about the first thing I did was change the oil. I went ahead and put synthetic Mobil 1 in, figuring that it'd be safer to spare no expense, especially starting off. I'm curious now though, does the synthetic make a huge difference in a non-turbo model? I guess what I'm asking is: does it matter?

Also, what should I consider as far as grades of fuel for it? I've been going with 91 octance, but figured there's no reason not to ask your opinions on if that's a good idea and how much difference it'll make.

well depends on what you want to do with your car depending on what you do fuel wise. Are you wanting to upgrade the fuel system or just know what to do to keep it running at it's best?

I may eventually upgrade, but for the time being, I'm just wanting to keep it running at it's best.

Well since you don't know what the car have went through. I personaly would put in injector cleaner in it. and let it go that's about all you can do. But if you want to upgrade then you have a lot of option's and when that time come let me know.