My shop has done hundreds of these repairs. There is never a problem with the bottom end. I have one customer with 650k miles on one (91 420SEL) and we have done two of such repairs to it. I felt bad when the first came back after only 120k broken again. It turned out that when we did the first one with what we thought was 150k it was really something like 300k (speedo had been replaced). When it got somewhere over 400k true it wore through the lower left side rail. When we did the first one we didn't go for that rail because it doesn't wear out till after 350k.
He has over 200k on it since the second repair and he repainted it a while ago so I guess he is going to use it another couple years (he drives 90k miles a year).
Bosch Master, ASE Master, L1
33 years MB technician