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Need some URM advice

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Can anyone tell me if the current UCBC Appendix Chapter 5 for Special Proceedure of URM retrofit provides a maximum diaphragm capacity when a plywood is added directly to the rafters. "In the old days" we were not allowed to take more than 225 plf in the diaphragm, but this was when plywood was applied over 1x straight sheathing. 
If this is not the case, can the UBC 94 values be followed for a diaphragm capacity. I am trying to balance the shear anchorage and diaphragm stiffness without resorting to crosswalls. Too stiff a diaphragm and I'll be penalized in the number of shear anchors I need to add. Too flexible the diaphragm and I'll have too add crosswalls to control the diaphragm deflection.
Any advice on the maximum allowed diaphragm capacity for a roof where plywood sheathing is applied directly to the joists / rafters?

Dennis Wish PE