Hi there! I'm the Founder and CEO of Allegorithmic. We make Substance, texturing tech dedicated to game artists. Glad to actively participate as of now!
Yep! that sounds about right. Allegorithmic has a lookup table in their documentation: https://support.allegorithmic.com/documentation/display/SPDOC/Unreal+Engine+4
There's also a Guide to PBR by allegorithmic available as an e-book. That one also for a good job of putting the info into usable context for an artist.