I recently sent a message to a guy selling a 7v on eBay to inform him of missing parts. Doesn't seem to have affected the sale, as the price is north of $150 and climbing with 2+ days left.
I purchased a 10v (also eBay) about a year ago. Looks to be nearly the same engine. I know that the 7a is slightly larger; 7.5" tall vs. 6" for the 10v.
I assume is has a correspondingly larger bore and stroke. Other than that, what are the differences? Why is the 7a so much more expensive than the 10v? the web searches haven't been much help.