I don't know on the 190 if there is the same easy conversion as the 300E. The bigger alternator will help but the deal with the 90- 80A alternator is that it produces at low speed. Fifty five amp alternators are just fine unless you just sit around and idle all the time. A seventy is not much better if it is one of the early designs. The later alternators can be distinguished by the output terminal being screwed to a 8mm lug rather than spade type push on terminals.
What makes the deal so sweet for the 300E is that a cheap harness is available from MB (its not intended as an upgrade its just the part on the later car and it is separate from the larger engine harness) and the 80A alt is actually cheaper by a few bucks wholesale (retail it isn't).
Bosch Master, ASE Master, L1
33 years MB technician