Like said before, lose every bit of weight that you can afford to.
Look in the 'Articles' section on
www.slantsix.org . Lots of good info there.
Slants will respond to the same things any other motor will. You just have to remember to be realistic with your expectations.
Biggest problem you will have racing a fairly stock Slant will be finding a sweet spot on the tree. I always had to leave in a spot somewhere between when the second yellow went off and the third came on. If I saw the third light on I was dead late.
Trust me, get lots of practice in and you can do very well racing a slow car.