Yeah, that cone is too shallow. Putting a 2" center-screw aluminum spinner on an engine this size is always a crap-shoot, when dealing with depth, and even the prop-notch can be difficult to fit correctly.
Do know, on that Saito, being a four-stroke, you need to run a jam-nut/prop-nut, really for your own safety. Note the original nuts with that engine probably were a prop-nut, then a jam-nut that seats and tightens to the prop-nut. That's for your own safety. A jam-nut is always recommended on four-strokes. If you ever have a four-stroke back-fire and throw a prop off, you'll know why you should always use a jam-nut/prop-nut. Don't leave that out.
Is it easy finding all the correct components to make it right?... nope. It is possible though.
A 2" aluminum center-screw spinner is actually small, and is a tough one to get fitted right, if it's even possible. Why do you need a 2" spinner?... is it for a cowl mating?.. I might suggest Tru-Turn spinners as well. Just Google them if you're curious. In my experience, they offer far more options and information for spinners of this sort then anyone... and they have many different shapes and sizes, and will custom make spinners/backplates as well. It's all they do, and they haven't changed in the 30yrs I've been using them. DaveBrown on the other hand isn't nearly as keen on spinners, although they offer somewhat of a variety. Tru-Turn makes spinners in every size, from very small electric styles, to giant scale and beyond. So if DaveBrown products doesn't come through, check out Tru-Turn, they will for sure help you.
Also, be aware not all prop-hubs are the same thickness. A MasterAirscrew resin/plastic prop has a very thick hub, whereas a Xoar or Falcon wood prop has a thinner hub and is overall thinner. So if you get your prop on, and there's only a thread or two left to put the nuts on, your prop might be a bit thick... again it's not easy sometimes to find compatible components, but it is possible, and well worth it, because with the props/engines it boils down to safety. Good luck with it.