The data I've seen online as well as anecdotal experiences from my friends is that the NBMEs range from underpredicting to getting it fairly close. I would say that that you're probably somewhere between a 184 and 200 if you were to take the real thing today. As for the curve, the curve on the real thing is definitely more reasonable than on the NBMEs. There's no way you need to get 85-90% correct on the real Step 1 to get a decent score on this than on the NBMEs. Also, pure speculation: it's possible that the NBME scale is warped by some people who look up answers during the test, which artificially inflates their score and thus the overall curve. Finally, it's totally normal for people to have scores in that range before they've started seriously getting into dedicated. I know lots of people who started out sub-180 and went on to do great on the real thing!