Scott my brother is building me a vox ac30 clone right now. The original has a lot of circuitry for tremelo (a waste if you ask me) http://www.obsoleteelectronics.com/VOX_Tech/vox_tech.htm
The secret seems to be in a good output transformer. Mine will have a master volume in the inverter circuit and a reverb. If you are interested I can possibly provide you with a plan or even possibly get my brother to "whip" one up for you.
scott, b4 tackling a vox,maybe try something a bit less ambitious. it is a beast to wire up, and has alot of things going on, that you need to understand. try twin or a bassman first? then onto to some high gain jobs, then go to the vox, IMO.