I don’t recommend the Mohican for your first MTB 100. It won’t be enjoyable and you can likely expect a 10+ hour day and possibly much longer. I’ve done 7 MTB 100s and last year I did the Mohican 100k for the first time. There are better MTB 100 for a first go (Lumberjack 100) that will challenging but less miserable. I did Mohican with 5 of my teammates most of which did the 100 mile and no one enjoyed it.
However, since Mohican is so close there’s probably no convincing you otherwise. If that’s the case, I’d strongly recommend the 100k. There is very little to enjoy about this course and the actual trails in the Mohican park are the best and easiest part. Unfortunately, that’s not representative of the remainder of the course. If it has rained within the last week before race day then god help you, you’re in for a bad day.