replacing old mixer taps with new - sizes

[gemma1234]

I want to replace the bath shower mixer on my old bath. The two bits of the mixer are currently about 155mm apart (I'd guess at 6" as they're quite old?). All the new mixers with shower fittings I've seen have their connections at 180mm apart.

So two questions:
1) is there enough tolerance in the new 180mm fittings to be able to fit them to the current holes;
2) am I just looking in the wrong place for bath shower mixers that would fit the smaller dimensions?

 

[advancemaintenance1]

if the new mixer you buy is on stands you will be able to fit in your existing holes not ideal but will fit just dont buy a solid mixer tap