I don't think you did any damage since you kept stopping when the temp was too high.I'm sure you know it's time for a new radiator now(hopefully with MB coolant).
The reason that it kept running hot was that you had an air pocket in the upper part of the engine. A very common occurrence on the V-8s. I used to do the initial refill of cooling systems through the upper radiator hose to prevent that from happening. If you get air trapped in the manifold and heads, it can take it a while to "burp". On most models it's a good idea to run the auxiliary water pump with jumper wires while refilling with coolant.
Regards,
Randy D.