Is this noise normal?

[digadam]

Hi there all,
I’ve slowly been getting things improved on the Mach 1. It has 351c 4 V.  I recently had brand new custom headers and exhaust installed, new push rods and gauge plates. It has a solid cam and solid lifters and my mechanic assures me he has the lash set correctly and that this “sewing machine “ sound is normal. He’s a bit deaf though.  What do you think? Is the tapping sound normal?  Thanks. Adam

https://youtu.be/p1-7N4FDf1o