Looking for insight as to what age the Labrador Male Head will stop maturing. First time Male owner and I'm not sure if they mature at the same rate as a female.

Depends on the lines. Mine looked their best around 3 yrs.

agree it all depends on the lines.
my younger boy is now 6 and his head widen a bit more around 5 yrs. old.

Not really the same rate as the girls. The girls can grow more width in their heads from hormones. Progesterone & estrogen. It can be with heats or with each litter. Depending also on lineage. Some don't grow much more after age 2, others will continue to grow with every litter and look their best as a brood bitch or veteran.
The boys heads can develop up to age 5 to 6. Age 3 you should have an idea of his basic head size. It can grow more. The pedigree has allot to do withit as pointed out already.
Especially a strong bitch line with nice heads will continue to follow through most of the time with either sex.