My bit of advice would be done ever assume that any bolts are central or that any of the tangs are at 90 degrees to the action.
Once headed up prior to drilling any holes or fitting any small parts hook on the barrels and make sure there is plenty of meat in the blank to achieve your dimensions.
Take time prepping your blank getting everything square, if your bandsaw cuts ever so slightly off 90 degrees that can make quite a difference in weather or not the line of the rib runs down the middle of the blank.
Im a fan of using an oil lamp.
Sharpen your chisels the best you know how.
Small riffler files can be handy.
Trust your inletting medium - don't second guess it because your nearly always wrong.
In the second picture when your are adding parts i use a sash clamp to keep the action firmly in the blank.
