an alternative would go back to bottom mount

lol well as stated above fabing the elbow would be your only choice unless you by chance find a used one for sale that fits. visit your local exhaust shop or the like and ask them how much it would cost to do something like this
good luck
edit: the way you described it you would cut existing parts and welding them together? its plausible but it would be easier to have someone fab a full piece out of scratch. it wouldn't be all that expensive i believe.