Hello Alan
I wholeheartedly endorse Bob's remark. If you try to find a model club, or better still, a model engineering society there is bound to be steam enthusiasts who can supply you with a great deal of knowhow and safety proceedures.
Safety Valves, Blowdown valves and sight glasses are only the first of things to be checked, after being layed up unused for a long time.
Looks like a nice boiler by the way
cheers Tom