John from your description of the makers marks on the model it does seem that it is indeed made of silver, the 800 in the oval indicating a silver purity 800/1000, as Alex mentioned.
It also appears the model is Italian, which is indicated by, the " lozenge" shape, the "star" mark, and the "number/letters"
The key to the maker of the model is to be found in the number letter code in the lozenge. Which you say, looks to be "908 M" There should be "two" letters though, not just one. Get out the jewelers loupe and have a real close look.

The letters are for code for the province in Italy where it was made and the number is the name of the maker.
http://www.silvercollection.it/SILVERSMITHSTO.html
Cheers!
zBret