There are reports that Glasgow Warriors head coach Hugh Campbell has a plan to transfer John from the pack to the back line, and the flanker has been moved to centre for parts of games when playing for his club side, Aberdeen GSFP.
But the teenager, who recently came out top in the team's sprint trials, has expressed his anxiety that the move could leave him in a positional no man's land - something that happened to former Glasgow player Roly Reid.
However, Ally, a player who has made a similar move, and who is just back from a successful spell playing for Sydney University in Australia, said in today's Daily Record: "I have played with Johnny and he definitely has all the skills and ability to change over.
"As far as I am concerned if you are good enough you should have a go.
"He is good enough and in my opinion shouldn't hold back."
Ally, who was man of the match, and scored a try in Glasgow Hawks' big win over Heriots on Saturday, added: "I wanted to play only in the back row but when our backs-coach Rob Ackerman made the suggestion to switch, I just went for it.
"Head coach Peter Wright was reluctant at first but he gave me a chance and I gave it my best shot. The rest is history."