I'd say skyline if they both have the same amount of HP. The supra will get wasted everytime off the line. There is absolutely no chance of the supra beating the skyline if the horse power is the same. Not unless of course driver error.
you can always take a look at Best Motoring Internation Vol 5. They show why the Supra won't beat the Skyline in a straight line. Thats 550hp Supra and 550hp Skyline.