That is odd, because
Honda Automotive Parts
Shows the auxiliary valve in the head, that is the tiny intake valve that lets a rich fuel/air charge in right next to the spark plug, in my shop manual they do not count that valve when they are listing it as a 8 or 12 valve engine, looking at the rocker arm layout there are also 12 rocker arms in the 8 valve 1.3L head, at least in the shop manual, they also all are listing a 3 barrel carburetor from what I can tell, something only the CVCC Honda engines had.
Either way, it seems like unless you need a new engine, swapping to a 1.3L is going to be an expensive route to go and from what I hear, parts for them are getting hard to find, so rebuilding one before you swap it in is going to be even harder and as I said already, it seems like if you are going to go to the work and cost of swapping an engine in, spending an extra 80 cents per fill up is going to be worth it and your mileage should be enough better with premium gasoline that it will make up for the extra cost in fuel so I would keep the high compression.