Hey RJ, if you’re wanting a Twin Reverb in a head configuration, keep an eye out for a Dual Showman Reverb, because that’s exactly what it is. On the flip side of that, if you find a Twin Rev. that you like, look for an empty Dual Showman Reverb cabinet (they pop up on ebay sometimes), and the Twin Rev. chassis will fit right in. Note that this only applies for the Dual Showman Reverb, the regular Showman and Dual Showman aren’t the same size.
The same rule also applies with Super Reverbs and Bandmaster Reverbs. I’ve got a Super Rev. cab on it’s way for my Bandmaster Rev., because I decided that I’d like a combo better after all.