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

I was messing with a junk 596 head as a test piece several years ago.
Filled the PR hole, 2.08 valve, really whittled the guide down, layed the ST waaaaay back.
Worked awesome.
Low 280’s, rock solid past .700 lift.

Then I was reworking some used previously ported J’s...... that had a pretty steep ST and were done at about [email protected] lift.
Started rolling the ST back....... busted through before I was even close to what I’d done on the 596.
So, I tried the intake port next to the one that was flowing 280...... broke thru very easily...... hardly layed back much at all.
Obviously some serious core shift....... which allowed that one port to be reworked in that area without breaking through....... but not at all representative of what you can normally get away with.