Would a 3 rib 1800 behind an ej22 or ej20t if I wasn't launching off lights etc?

It would be powering a buggy..

Isn't a 3 rib the 1600 kombi box ?

Would it what ?? Break or or be ok ! I suppose it will go bang if you flog it and drop the clutch and I suppose it would be ok if you dont any drive according. I have a 3 rib box (1600cc) in front of a EJ22 so time will tell but I definitely dont drop the clutch on bitumen. I had a 5 rib box (1800cc) in it to get me to the exhaust shop 3 kms away but clutch started in driveway as it sat there a few days with old battery and all of a sudden it made this horrible almost grinding sound the 3 kms home. This is in a baja. Dont know what the noise is so threw the 3 rib box in at this stage.

Either the EJ22 or the 20 T i would chose the 1800 five rib or possibley even the 091 six rib , don't even bother with a 3 rib as they will be to lower gearing for comfortable driving of any distance .
What size tyres have you got on the rear too

We have flogged the ring out of a 6 rib 091 box behind an EJ22 for 8 years now, and it is fine. I would recommend one.

and RJES make a good bellhousing to bolt them straight up using all subi flywheel and clutch. 002 or 091 dont mater much, just pick the right diff gears for you!

Or even better....bolt the matched Subie 5 speed up to your engine so that it's ideal torque and rev range gets used.
By the time you've bought an Adaptor plate or adaptor bellhousing there's not that much difference in price. Then you won't have any worries launching an EJ20T.

what sort of pricing for a trans from you guys subarugears

I would look at the subaru gearbox by subaru gears.
When I was off road racing with my old man years ago we the gears my hold up, but we were either ( with a 2 liter box ) pushing the pinion through the front of box or cracking the case near the drain plug. ( if it held up )
Look at subaru if you want to fit and forget!