Cylinder head casting numbers

[Groundfx]

OK stupid question of the day. Do the casting numbers on B18 heads have a significant meaning, for example the PR4 found on some. And if so are there some numbers to look for that designate a better head than others? Any info would be helpful.

 

[Spody02]

pr3 are itr heads, p72 is a gsr head, not to sure about the ls head

 

[dc2GS-R]

PR3 = B16A or ITR head
Better port design. ITR also has port work. Obviously a VTEC head

PR4 = LS
Non-VTEC head from a GS, LS, SE, or RS

P72 = GSR
VTEC, quench areas and smaller combustion chamber. Also has a different intake manifold bolt pattern than the two above

P8R & P75 = B20 heads. The P8R is the superior B20 head. Non VTEC