Regarding "full interior" being defined better, you're right. That's why this is just a peek at the rules and not the full thing. Basically it needs front seats, carpet, headliner, door panels, stock dash frame, and the column in the stock location. I'll repeat it: this is just chat, not totally official rules. Trust what is in the magazine.

And, yes, the cars need to be NHRA safety legal for the speeds they are capable of.
DF