Picture of 340/360 head porting....Mistakes?

More armchair quarterbacking.......

Imo...... you haven’t taken enough off that lump in the roof next to the guide boss, in the head bolt area.
That material needs to be completely removed for the “high effort” type jobs.
Along with more material removed behind the guide, making for more of a “boat tail” type shape.

View attachment 1715469745
Out with the 340 & in with the 410 stroker!