Not to be a bearer of bad news, but I am in Nor Cal and you will not pass SMOG. Also on my '74 the driver side stock manifold cleared fine, on the passenger side the triangle flange hits the frame. I do NOT recommend notching the frame.
You need to drop $10K on a GM E-rod engine to pass SMOG in California if you own a 1976 or newer truck.
https://www.gmperformancemotor.com/category/ERODE.html
also check out this video, this guy tried to do what you are about to
MG #59 - How hard is it to pass smog with an LS swap?
hope this helps, not being rude, just keeping it real, maybe saving you some headache