1. I found him to be a thief. OK, but not very natural.
2. I thought him to be a thief. OK, but a very formal/dated construction.
Do the both 1 and 2 sound OK?
Then
3. I found him a thief. No.
4. I thought him a thief. Same comment as #2.
How about 3 and 4? They must be awkward to native speakers - ?