Head Differences??

[Wildjames123]

I know the B16a2 and the B18c4 are slightly different in port and shape as well as CC,

Can anyone tell me if this applies to the B16b and B18c6 heads?

Are they essentially a B16a2 with port work?

 

[twinkie]

the same with port work, cams, and valvetrain upgrade.