Dear Edwin,
Your overall approach sounds correct.
I would not expect a perfect match to the mode shapes in the “NRELOffshrBsline5MW_Onshore_ElastoDyn_Tower.dat” file because I derived those mode shapes using ADAMS (with a flexible rotor) in place of BModes, as discussed in the following forum topics: Tower Eigenfrequencies of NREL 5MW Turbine (see my posted dated Tue Aug 28, 2012).
Please note that (FA1) is swapped with (SS1) and (FA2) is swapped with (SS2) in this excerpt from your post:
Best regards,