From where I sit it would probably be engine architecture and packaging if you consider money not to be an issue.Secondly, what is the percieved limitation, etc.
The injected VTwins that make good power are mostly 90 degree ones, with some older 60 degree designs hanging in there. You need a straight shot at the intake valve and airbox volume, and that isn't going to happen on a street Big Twin.
Carburetors are much more primitive, but that is their strenght when matched to a primitive layout.
100TQ with reliability is easy, the 100 HP to go with it is the problem.
I don't care how much power you put into a chassis limited bike, it may be quicker on acceleration but will become more difficult to ride and under anything other then perfect conditions probably slower over a course.
Even world class road racing teams detune their bikes to make them faster around a track over race lenght and the guys that ride them are in a world of their own.
It's real easy, you can spend a fortune trying to get a percheron into the Kentucky Derby, but it isn't going to win unless all the other horses die.