Can you take a photo from an angle that shoes what you've got? I see two different chainring setups in your photos and cannot find a Saga 47t on the web (that's related remotely to bicycles anyway). What you want to do sounds straightforward, but without seeing what you've got I cannot help.
Ignore the previous poster. I've been modifying cranksets to do what I want them to do for half a century. All part of the fun!
Edit: I just looked further and I think I see what you've got. Top photo. the 47 hiding behind the outer ring. Bottom with a round 39 in place of the 47. You are wondering if you can do this with an oval 39. Probably yes but the oval ring will probably have an effect on chain slack. I drew up an arbitrary oval and measured a 1/10" of difference in chain circumference as the cranks are changed. (5mm, so half on top, half on the bottom - basically 2.5mm difference in "perfect" hub placement for ideal slack. Your actual chainring, over quality of the drivetrain and your tolerance of less than perfect slack will decide if this is OK.)
All this is assuming you do not use a chain tensioner which is an easy solution as long as you have no ideas of going fix gear.
Now, going to the outer position will look better but if the bike is set up right , you will be moving the chainring 4mm or so out of line with the rear cog. OK but not ideal. More likely for the chain to be thrown off, especially at the slacker portions of the cycle. (You could go to the outer position and get a shorter bottom bracket axle to bring the chairing back to in-line but that is expense (including tooling or bike shop time) and another go-round of "does this work? Can I get it?")
Quote me (with more/better photos if possible) if you have more questions. I am not the expert on parts that are out there for modern bikes.
Last edited by 79pmooney; 04-11-22 at 01:24 PM.