The JZIP interpreter handles them fine and they are quite playable on the Zorkduino if given the "wrong" extension (i.e. z3 or z5). This affects A Mind Forever Voyaging, Bureaucracy, Nord and Bert, and Trinity.

Changing line 178 of zorkduino.ino from:

if (n == '3' || n == '5' || n == '7') // .z3,.z5,.z7 etc

to:

if (n == '3' || n == '4' | n == '5' || n == '7') // .z3,.z4,.z5,.z7 etc

resolves the issue.

In addition, V7 games were never really supported (or generated) by any interpreter, but V8 (i.e. 512K) games are quite prevalent as created with the Inform compiler. I am not certain whether zorkduino's virtual memory space would properly support a V8 title.