Gorgo-riffic!
Even though Steve Ditko DIDN'T do the artwork on these two issues they both have something to recommend them. Issue 20 in particular.
Lookin' good, Oh Green One!
Issue 12 features an appearance (guest shot, crossover... hmmm - do monsters "cross-over"?) by "Reptisaurus" (AKA Reptilicus).
Gorgo 12
Gorgo 20