Complex sentence: The KV-85 was created by mounting an Object 237 turret on a modified KV-1S hull, by increasing the diameter of the turret ring with fillets on the sides of the hull.
Split into simpler sentences: The KV-85 was created by mounting an Object 237 turret on a KV-1S hull. To accommodate the Object 237 turret, the KV-1S hull was modified, increasing the diameter of the turret ring with fillets on the sides of the hull.