dry sump oil pump on the street

Without adequate shielding I think that the life span of the cog belt drive components would be pretty short and it may not be particularly long even with good shielding. Unlike a cam drive cogged belt, all of this will be down in the road grime - not just one pulley. You'd probably just have to do it to find out what the life-span is. I was just looking at the Melling site and they apparently make an OE external, dry sump oil pump for the Ford GT, no idea how those are driven.