We investigate the effectiveness of executing SIMD workloads on multiprocessors with heterogeneous Instruction Set Architecture (ISA) cores. Heterogeneous ISAs offer an intriguing clock speed/parallelism tradeoff for workloads with frequent usage of SIMD instructions. We consider dynamic migration of SIMD and non-SIMD workloads across ISA-different cores to exploit this trade-off. We present the necessary modifications for a general compiler/run-time infrastructure to transform the dynamic program state of SIMD regions at run-time from one ISA format to another for cross-ISA migration and execution. Additionally, we present a SIMD-aware scheduling policy that makes cross-ISA migration decisions that improve system throughput. We prototype a heterogeneous-ISA system using an Intel Xeon x86-64 server and a Cavium ThunderX ARMv8 server and evaluate the effectiveness of our infrastructure and scheduling policy. Our results reveal that cross-ISA execution migration within SIMD regions can yield throughput gains up to 36% compared to traditional homogeneous ISA systems.