The BPE, Sidewinder, Speedmaster, ProMax, and a few other all get shipped in on the same freighter. Then the work begins but like you said the castings are so much nicer. Not sure if they weld up the same as Edelbrock heads or not.
You are correct. I have had conversations with speedmaster about buying bare castings by the pallet, to do in house. Same thing those other guys do. But as a one man shop, just couldn't justify building 30 sets at a time, to sell a pair on occasion