Having a RB play RB is what I would prefer. I'm not sure why you think a LB who has never played RB for us would be a better solution.
The academy youngsters haven't had a look in because we have a massive squad this year, people like George Smith cannot even get in the match day squad at times even with injuries, so the kids have no chance unless we are short in a particular position.
And we are short at right back.
Buchanan has played RB for us on at least two occasions- both last season, when we had injuries to both Moloney and Phillips. Paul Anderson played LB and Buchanan went to RB.
I just don't think it's a good idea to try an untested academy lad who I don't think has even been training with the senior team at RB in such a crucial game.
The lad is 16. He needs to be introduced gently into the team, not thrown in at the deep end at RB when we've just lost 0-6 in the previous game, have a sea of defensive issues and lack any midfield protection for him.
If we'd seen him before, it might be a different story. But it's a big risk when he's played 0 minutes of senior football. He might buckle under the pressure.