LS1 and L33 differences

Need to change out the 250 in my '79 Chevy Stepside. Are L33 mills now more available or are they still too new? Any physical differences between the L33 (hopefully $cheap$) vs the LS1 family? (definitely NOT $cheap$) Did L33's come with flywheels vs flexplates? Am I crazy? Have decided to keep the old girl. He he he, I love a demented plan. :) :) :)

flywheels are for manuals, flexplates are for autos... :yup:

LS3's are in the same LS engine family the untrained eye probably wouldn't know the difference in the two.