Hey Dad
Can't you read the rules? No porting & polishing!
I guess cutting the fins off falls under fitting it into the chassis so I think you're OK there...
That "tank cover" rule is straight outta the USAC book; I think it refers to the dorsal-fin over the top plate that they put on asphalt cars, and probably has no meaning in the dirt-track world. I never figured out what they were for anyway...