Hi. I found this page which is I think what you are looking forWhilst members ponder the answer to your question perhaps they could also think how to reduce clearance between the hood and the bodywork just behind the window glass by the hinge point.
That gap seems to have increased since the hood was treated with Renovo (cleaner,colour, and protector).
Hoods, what a pain no wonder hard tops became popular.
Concerning old Landies series 1,2 and 3 ever the bloody hardtops were like that!The gap is an integral part of the hood design. When you have the “heater” on full blast in a vane attempt to demist the windscreen, the air displaced has to go somewhere & it exits through those gaps. Also if they weren’t there & the seal was good elsewhere you wouldn’t be able to close the doors due to air pressure.
At certain speeds the gaps, as you describe, flap about making a rather endearing farting noise, which should remind you of the hey days of the small British sports car. These details are either engineered in to remind you of some of the frailties to be found in the car you have chosen to drive! Or details which the designers haven’t be able to engineer out.
If having a couple of gaps in your hood concerns you, you must never consider a Land Rover.
I would batten down tight all the hoods & hatched on leaving one of mine in the drive & the neighbours cat would still be curled up on the drivers seat in the morning.
M