In my witch hunter combat patro list.

Check it out here:

I used two gun servitor with heavy bolters in the retinue of my inquisitor. Instead of having two gun servitor( I HATE the models), I wanted to convert a sentinel into one big gun servitor. I want to combine the stats of the two servitors into one model. ie two heavy bolter, two wound, two S3 attack in combat etc. I plan to mount it on a bigger base.

Can I get away with this without too much opposition? Does the bigger base give me any sort of advantage? or disadvantage? Would you allow me to field this model instead of the two gun servitors? Any suggestion on modeling?