At the minute a well converted good quality LHD car will probably sell at a slightly lower price than an equivalent original RHD car, but as, hopefully, demand increases, there will be a great importance on originality if you want top money.
I know Franky won't like me mentioning this, but I'll use the 911 World as the example.
15 years ago, people paying top money were happy with a well restored Pre 74 911, as long as it looked right and was mechanically sound. Then after a few years they wanted one that was restored with Porsche parts. Next was the car had to be to its original spec, so a S that started of life as an E ,wasn't as good as the real thing. Then came Franky's hated matching numbers, original chassis, original engine and original gearbox, because Porsche kept record of this at the factory and you can get a Certificate of Authenticity from them for your chassis number stating all sorts of mechanical and trim details. They were the premium until 2 years ago and now the "Nirvana" is the unrestored original car.
The demand for the Pre 74 cars, has driven their prices up (about 400% in 4 years for a 911S), this has then kicked down to the 74-89 cars, which have now doubled in price over the same period, and are continuing to rise.
Obviously if you take this over to Z World, the 240 is considered by Joe Public as the S equivalent, and it's current rise will then reflect in the subsequent 260 and 280 models.
I know a lot of folk on here like to have modded cars, my own isn't standard after all, but be prepared that at sometime in the future, you'll be faced with the choice that if you do want to sell it, the closer it is to std spec, the more likely it will be to get the better price.
Just some thoughts, and I know there will be the exceptions to the above, the likes of Ian's and Tel's superbly built modified cars will always find a generous buyer
. That's a lie. If I had the money I'd just buy it 
