Have you tried a lower grit on the UI yet? It's box finish is 800-grit, if you haven't tried anything lower, give 600-grit or even 400-grit a try, it might save you from spending a lot on a new ball. If you do decide on a new ball, the GP2 will give you that little extra 'umph' that you need on weak pocket shots, or to just kick out those 10's!
As for pin placement, go with 2-3 or 3-4. I find 2-3 better for pin below fingers layouts, and 3-4 for pin above the fingers layouts. Top weight, anything in the middle of the range should do, like 2oz-4oz. I prefer buying from my driller because I end up only saving around $30-$40 from buying online (or elsewhere), and I find that my driller is more friendly and more often gives discounts, free thumb/fingerhole adjustments, coaching advise, etc.
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-Dino