"Restored" can mean a lot of different things depending on the current condition of the instrument and the result. Both will influence the "value", which is a term that also needs clarification. If you mean value in $$, the best indicator is what a similar instrument in the same "restored" condition sold for lately. There are probably a few records of these on the recently sold listings of auction sites, but the price paid will certainly vary according to many different parameters, only one of which is the condition of the instrument. With such an instrument, I would try to find several recent records and pay attention to how long these were listed, how well documented these were, as well as the condition. The only way to be absolutely sure of the $$ value of something is to sell it and see what you get.
Paris Selmer instruments in that serial range are usually the Centered-tone model, which is highly publicized as Benny Goodman's choice of instrument. Typically this adds some extra $$ value over other clarinets that were not endorsed by Goodman. It is presently considered more of a big band model, although its' use in the symphony is also well documented. It is worth noting that Goodman had a long career, and this instrument was not produced until late in his career. It therefore cannot be the model that made him famous. It's the other way around. He made this model famous.
The only way to know the intrinsic value it has as a musical instrument is to play it in a for pay context. I think that $$ value and intrinsic value as a tool for producing music are sometimes independent values. If a musician can earn $25/hr. with a $50 instrument, perhaps that one is more valuable than a $500 instrument that allows him to earn the same $25/hr. The only way the larger investment is displaced is if it appreciates over time, or guarantees him a higher pay rate. An expensive instrument is no guarantee of a higher pay rate. If the $50 instrument can only return $50 after it's use is over and the $500 instrument can return $1500, then perhaps the greater investment was more valuable.
