Standing Rigging Question

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I have a 45' Bruce Roberts (fiberglass), sloop rig, with internal chain plates and I'm in the planning stage to switch to external chain plates. The rigging on this boat is somewhat atypical in that the lower shrouds are not symetrically spaced from the main upper. The aft lower measures, from the main, 31 inches or 84.4 degrees. The forward lower measures, from the main, 80 inches or 75.87 degrees. The mast spreader has zero aft sweep and I can only assume the original rigger configured the lowers this way to prevent mast pumping? I've had this boat about ten years and the unusually forward lowers have not been much of a problem as yet, but the boat doesn't get sailed all that much either. I hope to cruise full time within five years and want external chainplates for ease of inspection and access. My questions are:

1) Does this lower shroud configuration serve any real purpose?

2) If I change to external chainplates and the answer to #1 is no, how should I configure the chainplates?