Sorry for the delayed response.
Yes, I've been busy - not only getting the BM's ready but also with other speaker designs too.
Anyway, you'd actually be surprised at how the Mag v4's will perform in 0.7 ft^3 (your total 1.4 ft^3 enclosure). If you line the walls with fiberglass insulation and then stuff the remainder of the enclosure with polyfill you will receive good results without the use of an aperiodic membrane. However, you can simply use a
ScanSpeak aperiodic vent available at Madisound if you want more low-end out of the system. All you have to do is drill a hole and mount the vent to the enclosure. The SS vents are pretty cut and dry - no 'tuning' (changing the stuffing density) necessary.