1983 LMC Please Grade, Also Have Questions Re: Zinc Bubbles, Over Polishing

The plating blisters occur during the strike due to a poor bond of the copper plating to the zinc and the expansion of gas within the two layers from heat. These blisters will affect eye appeal and the grade depending on the severity.

Here's a good writeup on those: http://www.error-ref.com/blisteredplating/

The lines as you correctly pointed out are caused by die polishing, there also evidence of extensive die wear on this coin, as well as the large die crack on Lincolns head. It's no surprise extensive polishing was necessary considering the tired state of the dies.

Looks to be in pretty good shape though, I'd say 66RD

Also a ridge ring is starting to show on obverse and limited amount of steps on reverse tells indication of later die states...nice looking cent for its age...66 seams close/right

Yes, is that a die crack--head to rim on the obverse? Appears to lead to a cracked skull. Cool.