The answer to the question above would be that the best way to combine the sentences above is the following one: Thomas Jefferson was such a brilliant writer that he was chosen to write the declaration of independence.
Such.../that sentences intensify the quality of the modifier (in this case the fact of being a brilliant writer). The emphasis on the NP expresses a remarkable situation. Paired with a that clause, the result of the remarkable situation mentioned in the main clause is shown.
