Maybe drop the IS on your C a bit further for some more REB, so he'll get more putbacks as well
I think if you drop the IS more then your C will have problems scoring and I pretty much want all of my 5 starters to be capable scorers. I believe that if you spread REB over all 5 players it is'nt all that bad if your C has only 14/15 REB
Although it's not specified, I'd suggest that if you're attempting such a thing that your big men also have OD in the double digit range. I've found over time that it's highly effective in reducing the amount of points given up, and should not have any noticeable impact on salary.