Complex sentence: MacDonald began racing in 1956 running a 55 Chevrolet Corvette on Southern California drag strips and at the end of 1959 had won over 100 trophies, all in Corvettes.
Split into simpler sentences: MacDonald began racing in 1956 running a 55 Chevrolet Corvette on Southern California drag strips. By the end of 1959 had won over 100 trophies, all in Corvettes.