wastegate hole
I don't think the elbows are exactly the same. Yes, they will exactly match the bolt pattern of the turgo, but the wastegate hole is slightly larger, as is the puck that covers it.
Atleast mine was slightly larger than my friends stock GN elbow and I am the original and only owner of the car so I know it was never modified before we took it off to replace it with a Terry Houston elbow. Don't know if that would affect your plans for your project. Just adding my 2 cents.