Hi, when I bought my JDM import last week I was not expecting to buy an import but realised the rarity of something a bit different once I viewed it. I was expecting a 260z 2+2 as advertised but it ended up as a JDM Fairlady Z 2/2. I would not be afraid of buying an import but the more history you can get the better with it.
With restoration, if you are not going to do at least part of the work, it will be expensive and in most cases, unless you are very handy with a spanner and spray gun, restorations cost more than you will get back selling it. I would consider a nearly complete or complete restored one personally in your situation. I have a fully restored one but not afraid to do mechanical work, I just hate rust and body work so pleased that is already done.
It seems that in most cases, the UK 2 seater cars cost a bit more than the 4 seaters so you may want to consider a 4 in a better state for the same money (think Hedgehogdodger is selling one). Only 18off 1975 model 260Zs exist now though, 10off 260z 2+2s and about 4 JDM Fairlady 2/2s so eventually the rarity value may increase! Beware of Euro and US LHD cars which have been changed to RHD badly. A good job is possible but not cheap to change well. UK and JDM cars all have RHD anyway from the factory.
I think it depends on what you prioritise, do you want to customise it (in which case originality is not so important) or leave it standard? Do you intend to track it (more power and big engines better) or show it (clean and original probably best) or just enjoy driving it knowing its a good car (history helps here and gives you something to talk about.
Good luck!