116 front suspension dilemma

After rescuing a 116 ('77 gray market 450SE) from a neglectful home, my mechanic discovered a substantial amount of rust around the control arm mounts in the front suspension. He advised that there isn't much to be done once rust takes hold in that area. This is an otherwise solid car that I feel is worth saving if possible. Has anyone out there experienced this problem? Any success stories? If so, what kind of materials and expense were involved?

Any feedback would be greatly appreciated!

Thanks,

T-dog

'77 Euro 450SE