My 175 and 178 loads are the same. You could drop it a little if you want and work back up but if you don't have pressure with the 175 i doubt you will with the 178
Also try to load it out to about .010" off the lands. This may not be possible in some factory tubes and still have the round fit in the internal mag though.
I use Varget with my 178s in my .308.