High-performance reconfigurable computing involves acceleration of significant portions of an application using reconfigurable hardware. Mapping application task graphs onto reconfigurable hardware is therefore of rising attention. In this work, we approach the mapping problem by incorporating multiple architectural variants for each hardware task; the variants reflect tradeoffs between the logic resources consumed and the task execution throughput. We propose a mapping approach based on genetic algorithm, and show its effectiveness for random task graphs as well as an N-body simulation application, demonstrating improvements of up to 78.6% in the execution time compared with choosing a fixed implementation variant for all tasks. We then validate our methodology through experiments on real hardware, an SRC-6 reconfigurable computer.