Leave factory under coating alone or replace it ?

I've never seen the factory undercoat the engine bay. It looks like someone did that. I had a 63 Dodge that I removed all the factory undercoating from under the car, (very time consuming & messy job) & all of the metal where the factory stuff was, was in excellent condition. I would leave the factory stuff alone, just pressure wash it real good & MAYBE go over it with a very good kind of undercoating. The original undercoating is pretty good, & I was told it has asbestos in it too.