This. I am probably in the middle of the pack, but I do have pecs and lats. Still don't need any space in the back. Would prefer a slimmer cut through the chest and shoulders so that it fits perfectly from day 1.
The real question is whether the body itself would need to be adjusted to have straighter cut. The jacket won't need to be optimized for riding, so excess leather through the shoulder could be taken out.
For this one, let's just say it's a cross zip, and work from there. Otherwise, there will just be a ton of debate, and we'll end up having to make a decision anyway. This from years of experience doing group mto pretty successfully.
To derail the thread a little, I spent a good deal of my life developing models, which has left me with a healthy skepticism about our ability to quantify ROI beyond the trivial. That is not the case here, but whatever.
The body will be customized specifically to fit slim. Beyond that, I think that there are some adjustments from a stock size (sleeve and body length) as for any Vanson mto. You will be able to choose your own leather.