camaro subframe problems

finally getting under my 1980 camaro to repair a fuel line i noticed a rusty looking spot on the rear subframe, when i started scratching it away with a screwdriver some of it crumbled and i found their was a hole about 1 inch in diameter. i know it can probably be repaired but can anyone tell me from experience or personal knowledge how it gets fixed.

Remove all the bad stuff, replace it... Lots of aftermarket companies selling floor and subframe structure for the Camaro's... Think you can buy everything for them from the aftermarket companies except the title and VIN plate.....