I can find several references showing an equivalent circuit, such as:
Cascode - Wikipedia, the free encyclopedia
**broken link removed**
Some are for a FET cascode, but that's easy to change, and you will probably have to add a bypassed emitter resistor for the bottom transistor.
The equivalent circuit is not trivial to solve, but this is the 21st century, and you have computers to do the number crunching.
I get a mid-band voltage gain of 122.3, a low frequency corner at about 3460 Hz and a high frequency corner at about 17.88 MHz.