Salaam
Top speed of a car just does not depends upon how much horsepower it has , it depends on a lot of thing .
- Horsepower
- Longer final drive ratio
- Drag coefficient
- Torque.
- Suspension setup
- Weight
"You can google the race between the nissan gtr, porsche gt2, ferrari 599 gtb and corvette zr1 and see for yourself"
Yes i do agree , but that race was done with a stock R35 .
The following GTR-35 in the video is tuned by Switzer and is known as P800 (800HP) plus with nitrous injection , which brings the cars HP up to 900 to 1000 HP.
So you are saying that it is only a matter of time (long race) that Bugatti will pass the Skyline . Hmmm !!! it is possible but the chances seems very slim for the Bugatti ..... Why you ask , because of Bugatti bad fuel consumption.....12 mins and the tank is empty. In the other words the R35 has to just use its nitrous injection wisely and make Bugatti run out of its fuel 
Have a nice day.
Bye.