I found a couple sources that suggest korean giant and yoinashi are fire blight resistant. From what I can gather, korean giant, yoinashi, and shinko are all compatible pollinators.

If I were to buy scionwood of two of these varieties and graft it onto the third, which variety would you suggest I use for the main body of the tree?

Shinko fits the bill. I have only one asian pear, shinko, and I have to thin the fruit. I do have a European pear, and there are ornamental pears in the neighborhood, so I can't rule them out as pollinizers, but Shinko is advertised as self fertile, as well as Fireblight resistant.

Alex

I grow both Shinko and Korean Giant. Taste-wise, they are at the opposite ends. KG tastes great, juicy, sweet and crunchy (just what I like). My shinko is bland, very bland. KG produces profusely. I thinned at least 600 fruitlets off last year.

Not so long ago, there was a tread in this forum about taste of Asian pears, It appears those who get good tasting Shinko live further inland. The East Coast people don't seem to have good luck with it re. taste.

I don't get fire blight (so far) on either one. Both have little to none of pear blister mites problem, either.

I am partial, I would plant KG and graft Shinko and other fire blight resistant variety to it. In my orchard, I've grafted KG and 20th Century onto Shinko. (first year trial, don't know if it would work yet). This is the only way that I can justify keeping Shinko!!!

I agreed about Shinko. After 3 years, I ended up removing mine and replacing with Korean giant at my backyard . Hosui is my favor despite fireblight susceptibility.

Of all 4 varieties I have, Korean Giant aka Olympic, 20th Century, Shinko and Hosui.

Re. fire blight resistance, KG is best in my area. Shinko does not get it but has other leave issue. 2oth Century gets some. Hosui is the worst. Not only fire blight, it gets some either mineral deficiency or some kind of virus, too.

I don't know where you are. Different location/climate may affect each variety differently. I am in New England/east coast.

If Hosui continues to give me a headache next year, I may kiss it good bye.

Hosui got fire blight for the first time in seven years for me. It is about a third of the tree. My Sugarsweet European pear and two Winter Banana apples have perished from fire blight.
Love, love, love the Hosui taste. Great fruit set and have to thin out the pears. Planted Shinko but am not overjoyed at the taste--bland and not hardly worth growing. However, according to literature, Shinko is very fire blight resistant.

Hopefully you'll get responses from people close to you. FB very much depends upon your area. Probably due to when the pear blooms, when there is rain. I grow 15 or so Asian pears in dallas, but my info would be pretty much useless in nc. Maybe VA is close enough?--I don't know--but we have several good va contributors.