The original Camaro was 186" in length, just a mere 4 inches shorter than today's Camaro. Weight was 3,500lbs for 1969 Z28 with 290hp. That's just 200lbs less than a 300hp, 3780lb., 2010 Camaro LS. Now, I'll fully admit to never have driven either the 1969 nor 2010, but knowing what I know about the Zeta platform, I'm gonna bet that modern technology more than makes up for the 200lb weight gain and that the 2010 can easily dance with the 1969.
A 1976 Camaro Z28 was 195" in length, 5 inches longer than a 2010. It weighed about 3680lbs and put out a fire breathing 165hp from it's 350 (that is actually up 10hp from the '75 model). Even a V6 2010 Camaro being 100lbs heavier would easily lay a 1976 Camaro to waste.
By the early '90s weight was back down to a more respectable 3200 for the Z28, but power was still a Miata like 170hp from a 5 liter V8. The 1990 Camaro was still 2 inches longer than a 2010.
In 2000, the weight had creeped back up over 3500lbs, but at least now you could get the venerable LT-1 to cope with the extra mass. Length was 3.5 inches longer than the 2010 Camaro.
One important thing to note is that even though the 2010 is the second shortest of all of the Camaro body styles, it easily has the longest wheel base which greatly improves handling.
Not being a Camaro fan, I just don't see, looking at these numbers, how the new Camaro is that far "out of line" from the original.