We use 20x15's on most of our projects. Most companies will widen 2pc hoops for you and most 3pc wheel companies make 15" wide halfs.
So, basically all you need to do is find a wheel you like that fits in your budget.
Also, you may want to reconsider using a 20" wheel for a car that will "spend time at the strip and very little street time". The sidewall will be stiffer and the compond will naturally be less aggressive than a drag radial type tire.
But thats my opinion. Here are some of our 20x15 project cars:
