Is there a way or is it good to paint inside longs Options

[wayne1234]

Well most know I have been doing alot of rust repair, and I have gotten near the end. The hell hole has been replaced and motor mount. and long material behind the motor mount... I used weldable primer on the back side of the metal. But I'm guessing that after welding there has to be some burn off. leaving some unavoidable exposed areas inside the longs.. some one had mentioned this in my rebuild thread.. and It got me thinking. What would be suggested to treat or coat the inside of the longs, then maybe paint them? I'm picturing a long wand like maybe a Ziebart rust proofer would maybe use? make a acess hole in the front of the long and spray around in there and around the heating tube as well? could you use phosphoric acid wash first then rinse then maybe a heavy rustoleum coat? the excess would come out the drip holes? looking for ideas. Thanks for all you input