Question about coupling/isolation transformers

[any]

Hey All,

A local electronics surplus supplier is selling of ISD1420 based voice recorders for cheap (US$16 for a whole kit including parts & pcb)
Thing is, I read it needs to be isolated through a transformer (like the Zvex Lo-Fi LJ) and I'm unsure which transformer would be best.
The same supplier also sells some Audio transformers, nemely a 3kohm Centre Tap to 3k ohm Coupling Transformer,
a 1K ohm Centre Tapped - 8 ohm Output Transformer and a 600/600 Ohm Isolation Transformer.

Any idea if these are usable? I couldn't find any specific info on which transformer to use...

Info much apprieciated!