Lyra Titan i with a Manley Steelhead....settings??

I wouldn't agree to avoid the coils on the Steelhead, I love the coiled coupled inputs, but I have tubed system. I hooked up solid state amps a couple of times, and what sounded good through tubed amps sounded almost phosphorescent with the solid state amps, so whether you use the MC or MM might be a matter of taste or system matching or the tubes you use in the 6922 slot. I find the MC input much more delicate and refined sounding on my system.
The internal impedance of the Lyra is about 5.5 ohms, so that would match with the 25 impedance setting if you use the MC input, but probably 100 or above with the MM input. It is easy to just listen to get the setting that sounds best, don't just rely on specs, that what you got the Steelhead for is its flexibility. You can leave the load capacitance at 0 with MC cartridges.
I believe that the 50 and 55 gain settings use just one half of the small triode, and the 60 and 65 settings use both halves, so you might try 55 and see if the sound is cleaner that way. I find that the 55 setting with MC sounds best overall, but they all sound great.

With coil inputs, the optimal power transfer occurs when the impedance of coil input is as close as possible to the cartridge impedance, which with the Steelhead would be the 25 setting for a Lyra with internal impedance of 5.5. With MM input and no coil, the rule of thumb is to use an resistance that is 20-50 times the cartridge impedance, which would be above 100, although according to taste and experimentation, you might like to go as high as 47k to get more 'air' from the cartridge. Again, you can tune to taste, even for the coils, although the volume will drop for the MC input above the closest impedance setting.
Input impedances are different for coils and straight MM amplification stages.