340X heads vs late model LA heads vs Magnum.

340dartley said
I am not sure but I thought late model 318 heads used the same port size as 360/340. I know the valve sizes are smaller but that could be changed.

The only 318 to use the larger port heads, as far as I know, was the E48 cop car engine of the mid-80s. The valves were 1.88/1.60 IIRC.