Are you seriously going to attempt to "restore" this car?
This is a parts car at best.

Please take very close look at the firewall and the inner front fenders, especially along the top of the inner fenders and verify that the structural member is sound. Any rust in these areas is terminal.

I've got parts SLs that don't look this bad....

R107 SLs are relatively cheap right now, you will be much better off to find a better example, with minimal rust.

Jim

__________________
14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles