...funny I just saw your other post with the blackplate.
I don't know how bad your car is (rust wise), ...but the trunk looks pretty darn good. (I know you have some issues on the dash), ...but what are your plans with the car? ...the answer to that would be the basis on what to do.
Ironically, my '67 is in a similar 'boat' in that I want to make it more 'presentable', ...it needs paint, ...but I don't want to lose the originality in areas such as the trunk, ...underneath, etc.
For now, ...I'm just going to clean, ...and then drive it. Eventually paint will be in the future, ...but the trunk and undercarriage will remain as is. You can always detail that stuff down the road if you decide cleaning wasn't enough...