I'm no expert, just someone that read and tried to understand the book. HPBooks "Aerodynamics for Racing and Performance Cars" says a teardrop shape with a length between 2-1/2 and 4 diameters has the lowest possible drag coefficient.
Therefore I would think in Streamliner class where you have approximately unlimited options of engine and driver placement and wheel arrangement, you would put the wide engine and drive wheels up front, then the driver, then the rear wheels in line for a narrow rear. Cars in 300-400+ range look like fighter jets for a reason, but you're not in that range.
With the flat engine in a round shape, I'm guessing there would be space for a legal window and line of sight above the engine so you wouldn't have to add a bubble for the driver.
I've always wondered if having the drive wheels up front pulling would eliminate the problem of having the pushing rear wheels trying to pass the front as air resistance goes up.
What kind of idiot uses a low displacement vintage VW engine for speed? Idiots like you and me. Power to you.