Topband: Reversable beverage wire question. SV-RBWD1

[Ffive VHN]

'allo,

I've got a SV-RBWD1 Feed & Reflector Transformer for Military WD-1A Wire.

 However I do not plan on using Military WD-1A Wire with it, I'll probably use twisted pair, telephone drop wire or bell wire. How much difference will it make ? 

I note that they sell different models for the other other types of wire, so there must be some difference. (SV-RBTP or SV-RB300)

Or can I modify the units I have ? 
I would imagine its 'just' a tap on the coil on the balun/core. If yes what values.

Thanks

Rob F5VHN (see you on THE band)