You will find that Swiss in pretty close to C&H Diamond Grain and the other premium powders of the 19th century. It is also dense enough to allow the proper charge weight in most instances.

Trying to get a double to regulate with Goex may be impossible. Swiss on the other hand might work.

C&H #6 is about like 1F granulation. The Gun and Its Development by Greener, at least my 1896 edition, has a wood cut of granulations of C&H powder.
My 45-100 with 100 grains of 1.5F Swiss will produce 1370 fps with a 530gr PP bullet it is slightly slower with 1F. This effectively duplicates or exceeds 19th century ballistics which are about 1350 with a 550 PP.

Dan