Size versus scale question

[Grimjack]

I am the very happy owner of a fair few Foundry and Sash and Saber / Steve Barber Models (can't remember which) 40mm ACW figures.

What I'd like to know is what scale works with 40mm sized figures? I want to possibly augment with plastic figures, especially in the case of cavalry but would like the option to add model kit items, etc. if possible.

[tom_aargau]

1:43 scale if you assume a person being 1.75 m tall.