Ju87G is far and above what the hurr2d is. It's not a modification, it's a standalone version. Been wished for a lot. Would be welcomed by many, despised by many (GVers).
Also, the Mk103 was considerably heavier MUCH longer (would not fit in the engine of 109s, for example, possibly was planned to be squeazed into a Ta152 which had more room, but never was), and this is why it had better trajectory (longer barrel, among other reasons).