The 440 Source housing from roughly 5 to 7 years ago had too small of passages to the lower engine block holes and definitely caused a restriction.

I have one of that version housing and have been dealing with running hot issues that changing most everything else hasn't fixed. (waterpump, thermostat, fan clutch all several times)

In a stock housing you can easily put your finger in through the front water pump area and into the curve where it goes to the block.

That's not possible with the older 440 Source version.

I just bought one of their new revised versions, the passages are definitely larger than the previous ones.
$65 shipped.

I haven't taken it over to the garage to compare it to a factory iron one.

If it's about the same size ports as the factory one I'll be installing it as is.

If it needs any reworking to make the ports larger I'll be doing that.

I'll post about it either way.

Hopefully it cures the run hot issues.