Those cloud 9 seats are very comfortable, I have one on one of my bikes and will get 2 more for the others soon, I can go 15 - 20 miles on that seat and not get a hurting or numb backside, or a major pain in the duffle bag area.....if you know what I mean...!
I also have concern about that top roller, those type rollers may not hold up too well to the stress that will be on it under power.... I could be completely wrong in this concern but if it gives you an issue you may consider using a skateboard wheel that is grooved out for the chain to sit down in nicely, they are made of very tough material and have 2 sealed ball bearings that will probably outlast the bearings in that China Kit type Roller.
You will know soon enough how it will hold up, but the main thing I want to say here is how awesome that bike looks, you did a great job on it and it's a bike anyone in their right mind would be very proud to have, much nicer than anything I have for sure.
Good luck on it in every way....!
PIC BELOW
The tensioner I made for one of mine using the skateboard wheel is not clean and neat looking but it works great and has held up very good on this bike...
Peace