you should also replace the camshaft seal, intake manifold gasket, exhaust manifold gasket, valve cover gasket, distributor o-ring, and the spark plug tube seals.
are you also replacing the timing belt & water pump?
go with the b18b cams. they will not cause any problems and you'll like the extra power. also, i believe the ports on your new head are bigger than the b18a.
the only thing different between a b18a and b18b as far as i have found are the head, cams, and intake manifold. the b18b is rated 17 hp higher than the b18a.