Gosd,
There was no B7A2"s" version in real life.
Aichi only made the B7A1 and the B7A2.
They had plans for an A3 model but an earthquake destroyed the plant before they could do any real production.
I have searched all sources available online and the "A" and "B" of Yashico's models were his designations, not an actual production model.
The only reference to a B7A2s I can find is when the article states there were only 80 B7A2s (plural) made before the earthquake.
DD