My sympathy goes with you
Brother of The Benz, Alex.
Sorry to hear of the faital misshap in your family, the loss of the head member.
Alex, if you haven't already committed the head to rest and resurrection, I might suggest an alternative.
Adsit Company, Inc. @ 1-800-521-7656 offers rebuilt cylinder heads for your 300E for $895.00 exchange. There is a $500.00 core charge pending the return and rebuildable condition of your old head.
This is a far cry less than any prices I've read in this forum.
If you can DIY or get Fellow Benz owners to help you, the savings would be humungus.
As to "Porting and Porting", you don't relieve a overhead valve engine, the performance improvement without a cam change may be so small that you wouldn't be able to tell the difference.
Many engines with super smooth port runners are intentionally stippled to better mix the fuel air mixture.
If the ports matching to the manifolds are off in size, this would be an area of improvement to consider. The gaskets are the templates to use. If you opt for a rebuilt head the valves would not have to be removed to do this.
If it were me I would go for the rebuilt cylinderhead and port matching.
Happy Trails Beep Beep from The Spiderman in Houston!!!