The Tamarack is about 1/2" deeper and 1 1/2" shorter in width than Bramble. I don't mind that it isn't as wide, because I wanted Bramble to overlap on the sides anyway. For the depth, I'll cut down the two side walls a little and then move the front back. The height of the floor is also 1" shorter than the floors above, which is just perfect for a basement.
The only thing I'm worried about now is whether the Tamarack side walls and one interior wall can hold the weight of the house above.
Other things I want to do with the basement are to smooth over the milled-in siding (that will end up being a log cabin finish on the living room and a stone finish on the laundry room), move some doors and windows around, and plan out some sort of entry.