James4,
Making it tough on us here.... You may be right on the bubble of a 150 working or a 250 working. Is the Silvertip centershot ? I think it is ? If so, you can shoot stiffer spine and get by with it, ( 250 ). You are also shooting dacron which makes me think you might be able to shoot a 150, but then again you are wanting to shoot about 200 grains up front AND a 29" arrow. I am going to bet a 250 will work better for you, but hopefully others will come along and help out. Why not get you a bareshaft of each and play for a while and see what shoots the best for ya ?
nocams