I'm sure he'd do a great job in the role, bring his own quirks to such an iconic figure in the Caped Crusader's gallery of rogues. But I'd rather see him take on a lesser-known villain who had only the one misadventure in the old 1960's show:
A villain who centered his crimes around books as the theme.
Wishful thinking on my part, but I always thought there was potential in the character. I think had there been less camp - and by that point in the show's history, it was too late for that! - and if McDowall had been available, the Bookworm could have been as serious a threat to Gotham City as the Big Four: the Riddler, the Joker, Catwoman, and the Penguin.
But this will prove to be just wishful thinking on my part.....