Ok, so on a scale of 1-10, one being I'm fine, 2 being I need to start praying for my bank account how screwed am I.
I pulled off the trans on the 1990 rx7 I recently bought to replace clutch as the old one needed replaced because the shop who previously did the clutch put a used one in it (according to old owner) and the throw out bearing was "going out", long story short, the bearing was in 7 ish pieces and had broke a few finger and bent the rest on the pressure plate, there's no damage to the interior of the trans housing however it has a thick coating of grease/oil that's super hard to get off, could this be an engine/trans leak or possibly from the shop where it was replaced at last used too much assembly oil or some lube on the bearings

 

Its pretty normal to see that oily substance on the inside of a trans. It's dust from the clutch thats accumulated in the bellhousing over the years and is contaminated with various things. Spilled oil from oil changes, potentially coolant, condensation... you get the point. I would brake clean it and scrape it and brake clean it and wipe it clean. Unless you see rear main seal leakage when you remove the flywheel for surfacing, I wouldn't be concerned as most I've seen have some for of black buildup in the bellhousing. Be sure to replace your pilot bearing when replacing the clutch as well.

 

welcome to the board.

one thing you could do is put some on your finger and smell it. if you smell gear oil (which has a distinct smell), then you may want to change the front seal on the transmission before you button everything up.