383 power upgrade help

I'd say 440 source heads from what I've had my hands on ( several pairs) are equal in quality to the rpm head and better quality than Edelbrock e-street heads.
The internal parts like seats and valves are not high quality but not bad with stealth.
E-street has cheaper parts.
Which is why both heads are affordable.
I personally have had to do much more clean up work on e-street.