Arne’s drawing of the two superimposed rigs is worth a thousand words.
With the mast position you would have preferred, Arne’s rig may be the more appropriate choice.
I would keep an open mind. These rigs have been carefully worked out and each should be regarded as a package. Some running parrels are needed to manage Arne’s rig which should not be needed on the SJR, but the other side of the story is that the SJR package includes running parrel-downhauls (which need to be tweaked each time the sail is reefed) which Arne’s rig does not need – and if you are going to have 5 lower panels in your SJR, then you will probably need at least three of these.
With the conventional junk rig you have a little more “wriggle room” too, ie the balance can be varied a little.
I have a question for Arne.
A number of SJR conversions (including my own) have demonstrated that if the geometric centre of the SJR rig is about the same as that of the original Bermudan rig, then the helm balance can be predicted to be about the same. This rule of thumb was pointed out a long time ago by Slieve, and saves the need for a lot of theorising if you have a drawing of the original Bermudan rig.
However I have not seen this approach applied to other rigs, such as Arne’s, so I don’t know if that rule of thumb would apply. Maybe Arne’s rig would need a little more (or a little less) lead compared with the original Bermudan rig?
(This post crossed with Slieve's.
I feel a little uncomfortable with the photograph, and if you don't have an accurate scale drawing to work from, then you do need to be confident you have the correct geometric centre (CoA) for your original bermudan rig, and use this as the basis for future calculations.)