The only different option when configuring the Aurora IP is the C_LINE_RATE, set this to 25.78125 Gbps, which can be generated by the 161.1328125 MHz reference clock.
set_property -dict [list CONFIG.C_AURORA_LANES {4} \
CONFIG.C_LINE_RATE {25.78125} \
CONFIG.C_REFCLK_FREQUENCY {161.1328125} \
CONFIG.C_INIT_CLK {100} \
CONFIG.interface_mode {Streaming} \
CONFIG.drp_mode {Native} \
CONFIG.SupportLevel {1}] \
[get_ips aurora_64b66b_0]
In these configurations, the AXI stream ports data width per lane is still 64 bits, so the AXI stream interfaces work on 25.78125 GHz / 64 = 402.8 MHz.