Re: Can I use a 5th string saddle on the 6th string?
String height needs to be radiused.
So if base is flat saddles are radiused,
if base is radiused saddles are flat.
If saddles are radiused then 1st and 6th are the lowest, and 3rd and 4th are the highest.
In your case either:
saddles are same, where you do not have any difference
or 6th supposed to be slightly lower then 5th, and your 6 th string is raised a bit.
And that is the best string to be raised if one need to be,
in both cases you are allright,
e.g. problem would be if you swap 3rd with 6th.