The proportions are right - the Savoy calls for 1 wineglass (=2 oz) "Mixed" vermouth and 1 pony (=1 oz) rye whiskey, along with 2 dashes of Maraschino (or curacao) and 3 dashes Angostura. Jerry Thomas omits the "Mixed" from the vermouth (weirdly enough, it doesn't specify sweet or dry), and calls for "bitters".
Ooh loved this! Had to do a 1:1 mixture of dry and blanc Dolin as it was all I had. One dash Fee brothers whiskey barrel bitters, 2 dashes Fee orange bitters. One Maraschino cherry, "if preferred v sweet add some maraschino cherry goo" ;-) YUM!