[Moppie]

Well all the B16a oil pumps are the same, so no trouble with useing one from a USDM engine.
And I believe the B18c pump is also the same, but you can check that when you buy a B16a one (as they will have the same part number).

Do not however use one from a B18a or other non-VTEC B series engine. They run lower oil pressure, and it might not be good for the higher reving VTEC equiped engines.