lets go dirt track racing
i think '74 & up valiants had 111" wheelbase too
a lot of them have very specific rules governing the cylinder heads also. you should be ok if you just use plain stock heads. but they are very competitive a lot of those crews eek out every teeny bit of hp they can. this is one area you will have to investigate thoroughly and make sure you are legal.
also an article for inspiration:
http://www.allpar.com/history/mopar/lapping-valiant.html
they did all types of racing in the challenge, including dirt oval