Interesting analogy but am I correct to assume you're referring to the practice of taking an older model car and upgrading it to be like the newer model? If so that's very different from an NSX-R conversion. It would be more apt to compare these GM F-body upgrades to a pop-up headlight NSX that gets upgraded to a 2002+ model.
Ultimately price will be determined by rarity + demand.
Modifying the early cars was more about putting a V8 in a 6 cylinder car, bigger wheels and tires, floor shift instead of column shift, manual instead of automatic. Four speed trans instead of 3 speed, paint jobs, change in seat material from cloth to vinyl (Naughahyde ) etc. There was no updating as the body parts weren't compatible from year to year. I suppose a person could have converted a whole 55 Chev to a 57 Chev as the chassis were similar but there was no point as 6 cylinder donor cars from all years were plentiful. It was more about mods to go faster or look different, very much the same as today.
I agree price is determined by supply and demand.
However just because a car is rare, doesn't mean it's value is high.
Let's look at an example from Ferrari, the 288 GTO.
Produced in small numbers, similar to a type-r.
A 308/328 owner can buy a body kit and the other needed parts to convert his car to a 288 GTO clone.
This is essentially what you are considering doing to your base NSX.
The 288 clone is rare indeed, even rarer than a real 288 GTO.
And a RHD type-r clone would also be more rare than a real type-r.
A LHD type-r clone would be rarer still, maybe one or two?
So the rarity factor is there for both the 288 and LHD and RHD type-r clones.
Now how about demand?
The first question might be how many potential Ferrari GTO owners would want a 288 clone rather than the real thing?
Not many judging by the price you see on the few 288 clones out there.
Then how many potential NSX owners might want a RHD type-r clone which would be the closest comparison to the 288 clone.
I've no idea if anyone in Japan (or other RHD market) has done this so I can't answer that.
Lastly how many potential NSX buyers would want a LHD type-r clone?
You would be a potential buyer for a LHD type-r clone as you're considering building one.
Would you pay a large premium for a LHD clone?
My view is anything done to a car that reduces the number of potential buyers will also reduce it's value.
I think that's why stock units tend to hold their value because they appeal to the largest possible buyer base.
As you mention, modified versions may appeal to a smaller buyer base and so tend to have less value.
Building a correct type-r clone would be a fun project and as you have a donor car you can do it quite readily.
However, and I may be a voice of one here, I would be cautious on thinking you can build one and if/when it comes time to sell, find a surplus of buyers bidding up the price of your clone.
I wouldn't confuse demand for type-r seats, or type-r shifter knobs with a type-r clone, but I'm sure you could part out your clone and do well.
If you are wanting to build your type-r for your personal pleasure in driving a type-r clone then as RPM217 says above, it's your money well spent.