Anyone ever make needle drops of acoustic 78s?

I'm transcribing some of my great grandfather's old hillbilly 78s right now. He appears to have been most active in his buying right at the switch over from acoustic to electric recording.

I've been importing to Sound Studio using the tape head input on my H.H. Scott 130 preamp, so it's flat. However, some, but not all, of the records have a lot of hiss (basically the Columbias are fine as is, but the Okehs are noisy).

What frequency can you pretty much safely cut out with no loss to the music, and would you recommend a roll off or a cliff?

 

Hmm, through experimentation, it appears a low pass filter at around 8.5 kHz does wonders.