Bill Tindall, E.Tn.
I forgot an important point. Wheels sold for bench grinders are limited and hard. One has to look for "surface grinder wheels" to get much selection for sharpening.

The soft Norton 3X wheel you found, if crowned, will surely be effective and the price is not onerous. I'd try it if I was in a buying mood. If someone wants to send me one I'll evaluate it compared to what I use. It will be returned crowned, however.

I know a pink wheel in H or I bond will be effective. A true "ceramic" wheel even harder will likely do well. I am reluctant to recommend a particle size. I don't burn at 120, but this wheel was custom made by Radiac. I thought at the time the finer particle size would better prepare the bevel for the next step. I now think wheel particle size irrelevant when followed by diamond and probably any other sharpening regime.

Beginners are going to have to learn control- how to sweep back and forth with light pressure without mowing off the end of a chisel. The problem will not be how slow this grinding is, but how fast. Once I get a straight edge I never desire to loose it. That is to say I grind to near the original edge, but never to it or beyond. I despise straightening crooked edges on the following "stone" step.

So, what particle size to buy will be governed by what can be found for sale and how well one can control the grinding. I know I can grind at 80 or even 60 grit. With a thin Stanley blade, 60 grit is breathtaking fast. Recall 7 passes across a 120 grit wheel established a hollow all the way to the edge. With the massive hunk of steel in a LV shooting plane, not so fast.

I used to get 1/2 x 7" Radiac wheels on sale from Travers for $12 not long ago. I see prices have risen a lot with $30 or more common. Don't know if there are still sales as I don't get sale circulars any more.