That doesn't mean they might not find the error and cancel it later. I had a similar situation where I went to DMV in-person for a used car purchase and was given a clear tile, registration and tags. 3 months later, DMV sent me a notice that the car actually had a salvage title, tags were revoked and I had 14 days to surrender the vehicle to a state police inspection or never drive it again.
Assuming you are talking about the older strong STi 6-speed, no, it's much larger. Requires a shorter driveshaft and shift linkage. I think the mount is in the same place, but I could be wrong...
I don't know about the newer split case 6-speeds, they're not nearly as strong, so likely not as physically large as the STi ones.