The OP said they needed to be all leather ... Beware!! Not all "leather" shoes are "all" leather.
If it works, great ... though I'd hate to ruin a pair.
Better to start with them fitting when you leave the store!
I have the worse feet to find shoes to fit. Add to that, the joy of wearing orthotics. I've learned my lesson on fitting ... and now am overly cautious when buying.
I used to love shoes and shoe shopping and now I dread it! :(