This is where the interference is:
View attachment 1716147086
The downleg of the exhaust manifold is designed to closely hug the factory head and block in order to give the maximum amount of steering column clearance. The early manifolds did not have to contend with the enlarged exhaust port pad introduced on later heads to accommodate air injection ports. The Eddies seem to have carried this design feature to an extreme, in addition to also beefing up the bottom edge of the head along the head bolt bosses.
View attachment 1716147095
The later 340/360 manifolds will clear the later factory heads, but I'm pretty sure you're still going to have issues with them on the edelbrock heads.
The solution is exactly what
@Jim Kueneman laid out- use a bare header flange to space the manifold out a bit, along with a slight bit of judicious grinding.
View attachment 1716147098
You'll only need to use one on the driver's side.
DO NOT be tempted to simply grind enough clearance entirely off the head. There are water jackets in there just under the surface, and I have hit them on stock heads- I don't imagine the Eddies are much different. Play it safe and use the flange.
