The only major difference between the USDM and JDM motors is the cams, that and the JDM motors will only have about 30,000 miles on them. The USDM D16A1 motor produces about 115HP while the D16A1-ZC motor puts out almost 140HP. Either engine will install exactly the same, and you can either install all the FI electrical from a donor '86-'87 Integra or construct a carbed manifold for it (ask cvcc_wagon for some advise on constructing a manifold).
If you decide to go carbed use the '86/'87 motor since it has a vacuum advance distributor. If you decide to go FI then you can also use the '88/'89 motor since you will have to install all the electrical anyway. The advantage of the '88-'89 D16A1 is that it uses an electronic advance distributor, ELD (electronic load detector), and a VSS (vehicle speed sensor). The '88/'89 motors also produce slightly more HP due to the domed pistons (higher CR) and larger intake plenum. The disadvantage of the '88/'89 motors is that thay have weaker connecting rods than the '86-'87 motors, but this shouldn't be an issue unless you're planning to run a turbo or NOS.
Oh, and about the 10 Hp more thing, I was just trying to put things in perspective. To me it seems that you would be putting alot of effort into swapping in a motor that won't give you much gain, when you could spend less effort rebuilding your stock motor to produce just as much power or swap in a D16A1. If you wanted to go through all the trouble of swapping in a motor that won't directly bolt in, you'd be better off swapping in a B-series motor. Granted there are more aftermarket parts available for the D16A6, but power is limited without spending alot of $$$. This is why most people with '88-'91 Civic/CRX's who are looking for more power either do a mini-me swap (VTEC), or they swap the D16A6 for a ZC motor.