My feeling is you should build it to suit you.
A little story - Mine is pretty highly modified. I have a BDA engine, an NG-3 trans, rear disc and front vented discs, twin link rear suspension, cloth interior, 15" modular wheels, a bubble in the roof and some other things. Some pictures here:
http://www.lotustalk.com/forums/f221/hi-nc-89399/For the last US Lotus meet, I made an extra effort to polish and pretty it up for the "people's choice" awards (people voted for their favorite example of different Lotus categories). There were between 6 and 12 Europas there and they were all very nice. Some were pretty original. All of them were much more original than mine. It seemed to me that none of them got as much attention as mine got. So when the awards were given out, I was disappointed that I got a third place. Then I figured that whatever "they" were looking for, apparently I didn't have enough of it for a first place, and that was fine with me since I didn't build the car for them, I built it for me. It seems that more people are more interested in "original" Europas than I thought. While there are things I wish I had done differently, I'm happy with it.
The moral of the story is to make yourself happy. It's your car and your money. There's no wrong answer as long as you're satisfied in the end.
Good luck and keep us informed about your progress.