Welcome Tom, The rule books just came in from the printer and should be hitting the mail very soon. As to your question on the cage the rule book is going to be your friend, The SCTA would like you to use mild steel @ .120 wall unless you have a pro shop build your cage as chromoly can become brittle at the welds if not anealed afterwords. As for tires how fast/what class are you looking at?
Agian welcome to the LSR world and enjoy!
As a side note we also have a LSR E-mail list to answer questions too. Look for it when you enter this sight.
Good Luck, Mike LeFevers