I would go 15".  Number one this is the stock wheel size that is used with
the 5-cylinder motor in SA.  Number two you can get big tires on the 15" rims
too.  Number three you need 15" (or bigger) wheels if you want to install a
set of the bigger, front vented disk brakes that I am supposed to be getting
from SA any time now.  A great add on for any engine conversion where you are
going to be increasing the engine horsepower.
I am trying to get 15" steel rims right now too (for you off roaders).
Ken Wilford
Van-Again
John 3:16