Hi David, yes cut the ones on the lower side to level the seats up.  Not sure if CLC's ones are pre-cut for the longest length, so you might need to cut all of them down, at least some degree, to size.

 And don't forget that the two seats are in different positions fore and aft relative to the center thwart, so the slope of the sheer (and therefore the cuts needed to make it level) will vary for each seat too...

I would not trim the seat level untill I paddled the boat. Most canoes that have slider seats ( for trimming, not rowing) tend to have the seat tilted foreward. I think you will also find that the seats are a littlte too high in this boat. Making it a little unstable. Bell Canoes offers a seat mounting  kit that will lower the center of gravity ie lower the height of the seat, very welcome on a windy days and really a must if you plan to paddle solo...just my humble opinion

Thanks for the feedback.

I will wait until i have paddled to adjust, if at all.

Thanks for the tip opn the Bell site. I do like there seat with the dip in it, rather than straight across. Also i like the web versus the cane which looks uncomfortable(we shall see).

Happy Paddling

David