Fitting stair case newal post on landing?

Fixing a newal post to first floor landing return.
Some clown took the original rail, balasters and newal posts out and built a fancy wall god knows why it looks gross!. How do I secure the newal post to the rafter. I thought of cutting the base of the newal post to form a half lap joint drop it in place and use coach screws to secure it to the ceiling joist and stringer. Would that be sufficient to make it secure? or other suggestions please. [keep it clean]
Thanks Rob