Speedmaster intake porting. Hopefully I can make something out of this

I agree. It is tons cheaper than the worthy Edelbrock manifold. As a basic upgrade, it’ll work just fine. I’d treat that SM intake like a OEM iron intake or worse. I wouldn’t even put much of a cam behind it to power it.
If your interested in making a good 5.2/5.9 into a nice street engine above just simple bolt on parts, the Edelbrock is the way to go. Couple up your base Magnum with a cam to suite and Edelbrock's intake and your on your way quite well IMO.