Would be interested in opinions on reiver's suggestion.
He's absolutely right. There are some caveats though, one of which he hinted at.
1) The pin on the large chainring is there to protect the crank from having the chain fall (and wedge very tightly) between the two chainrings. When this happens, your ride is spoilt and it is a carry home. Also, you'll get serious scratches and gouges on your crank.
2) Some chainrings are too sophisticated for turning. They have ramps machined into the inside of the large chainring which really improves shifting. By flipping it, you'll lose that benefit. Even by advancing it, you'll lose the benefit because the position is matched to a shortened tooth on the smaller ring.
A note to the OP: When photographic a chainring for judgement like you did above, show us the whole ring. Wear is accentuated over a small area only, which can be by superimposing a horizontal crank on a clock face. . The wear will be in the ten minute region between five-to and quarter-to. It will be clearly visible by a change in tooth profile.