It's a pretty cool amp. Treat it like a JCM800 with a slight pedal boost and you should be happy. It's more flexable than a JCM and for a short while was used on a lot of Jim Varney produced records. Michael Faith and Al Pitrelli used them and had some cool tones. A total sleeper amp.
i had a 120 watt version of that head. Sounds grand with the right valves, and yup, it's a JCM800 clone, and after a lot of mods became the 5150 (which I use now).