Gotoh today makes some excellent tuners. The 510s that I've experienced on guitars that I tried (not owned) were so buttery smooth, with a great ratio and stability. Many high-end/expensive acoustic guitar builders use them (e.g., Goodall), and I've seen them on electrics (e.g., Gotoh makes the Collings-branded tuners; if they're good enough for Bill...). Search Gotoh's website and Stew-Mac's website. Maybe current ones will fit the existing holes on your awesome Ibanez?