Realistically, probably a dead key of 5 to 8 watts and a swing of probably around 15 to 20 when modulated (mic is talked into)...it should have a 1969 final in it. Most shops will tell you they are getting a lot more than that, but they have loose meters that report "feel good" watts!
If you want to mail it to a good shop, PM me...there's a guy in Carlilse, PA you can call (and check out on the web as well) that has done good work and is highly regarded. You could quiz him and see what he has to say...