The amount of heat generated by 2 430 watt bulbs is much more than a single 1000watt bulb,i know nothing about the electrical considerations but i do know about the heat issue
not a good idea man, i would just invest in the proper ballast for the right light bulb, there is nothing like worrying about a fire man, peace of mind for sure
Usually bulbs need to be matched to the ballast in order to work. With the bulbs and ballasts I have seen it just will not fire the bulb up if the bulb and ballast are not matched.