A ported box is just as succeptible to leaks as any sealed box is.

Taken from JL's site...

Sealing the Box
Whether you are planning to use a bandpass, ported or sealed box, sealing the edges is very important (isn't everything?). The first step to take in assuring a good tight seal at all joints is to use copious amounts of wood glue. Don't be shy with it--keep a wet rag handy to wipe up the excess. Like bracing, you can never use too much.

Even if you blocked the ports, I doubt that the ported (no sealed) enclosure will be the proper size.