For what it is worth Paul I have a low number 240 (408) and I have almost completed (ie 99%) a 2.5 yr full resto on it. It's a full-on tarmac rally car but visually I have kept the original lines with only adding factory spec front and rear spoilers, as well as a 432 grill. I have original brand new 240Z door mirrors on both sides. Rims are after market but are Nismo branded Enkei rims. Interior wise I have a full welded in cage and Velo race seats but have kept the full original interior (all brand new) to keep its originiality plus an aftermarket Nismo steering wheel and gear knob. The whole interior is black so from a distance you don't notice the full cage and race seats. Mechanical wise it has a full race spec L28 (as original L24 was lost) running triple 45s (making 154 rwkw), with adjustable struts, R32 front calipers, R31 rear calipers and R200LSD. It has been resprayed in its original factort spec red which is actually a very nice colour red. Thus from a distance its looks very original except for the rims (and large exhaust); it's only on closer inspection that its real purpose is identified.
My navigator has just purchased chasis 232 but as it is a complete car with matching numbers he will restore it to full factory spec and keep it as his Sunday driver (he has an STi as his daily one).
Ultimatley the above two early build cars have different purposes and are being restored accordingly. And therein lies your answer. Restore it to how you intend to use it BUT if you do modify it keep it to factory options for visiable things given yours is a complete matching number one. And for originality respray it it's original colour (which is?) But that's just my opinion......