Before you think I'm a moron, I'm new to wrenching (learning as I go). And I know any rust is usually bad (I live in Northern NY, where is rust is a base color)

I took the tank off my 99 RKC to install new throttle cables. It say empty/dry for about a month. When I reinstalled it, I heard the rust rattling around and I took about about 1/2 to 1/3 teaspoon in loose rust. Looking inside the tank, there looked some surface rust around parts of the tank.

My question is how much do I need to get off? or how serious that can be to my fuel injection system?

Have read about using nuts, bolts, change, BB's, etc to shake the loose stuff off, then seal it with some type of product.

Thanks in advance !