Thermoquad identification help!

Hi there, I recently picked up a TQ and id love to rebuild/get it rebuilt professionally. I've been searching threads, forums, and elsewhere on the web trying to figure out what year it is and basically the basics of it. It's got 1.5 inch primaries so pretty sure it's an 850 but I'm new to these beautiful creations! I'll post some pics I know there's some gurus here that will know more than I! The two numbers stamped on the back driver corner are 9117s and 22977. I'm really just curious if it's a good one worth rebuilding? Id like to put it on my 360 paired with an rpm air gap. Running a Hughes cam .540 lift and comp roller rockers/push rods. Thanks!

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