1973 Plymouth Duster repair and rebuild

Hopefully I dont need to start a new thread for this question.

Lets assume I am going to weld the shock hoop on the chassis.

Here is what I see I need to do...

• Remove the shock hoop from car
• Pull the HDK 1/2 in sleeves
• Clean welding surfaces with flap wheel
• Weld/fill the 9/16 hole on the outside wall of chassis
• Weld/fill the 3/8 hole on the inside wall of chassis
• Spray Weld-Thru primer on chassis
• Clamp the hoop in the correct location
• Weld
• Paint

The issue that caused this problem is I had to over drill the outside chassis holes to 9/16 to allow some wiggle room for the bolts to go thru the crush sleeves and chassis.

My question/concern, what about the exposed weld on the inside of the chassis. Isnt that going to rust? How to I protect against that if I dont have access to it?