Frame damage suggestions

[hilltop55]

I purchased this 68 short bed fleetside in January this year and it's finally time to start the resurrection. I'm looking for ideas from the group to fix the rust issues on the frame near the rear spring cross member. I'm going to do a 4/6 drop so I was thinking of a c notch kit and maybe a new rear crossmember? Also I know that rivets are pressed in and replacing rivets with grade 8 bolts may be a issue? any suggestions welcome. I'm a motor builder but my welding sucks so I will have someone with skill fix it. Thanks Lou