How can you identify a big block car?

[Ramjett54]

I have a 68 camaro convertible date 03C
 it has a 2.73 12 bolt non  posi date 3/20/68
Yes it has the big block heater box
It has big block engine mounts
It has 68 396 engine date g 10 8 and 400 transmission
Console with gauges and tic tick tach
The vin stamp has been milled but you can see a very faint stamped Y
I am trying to discern if this is a true big block car
is it possible this is the original engine?
What other things are  unique to a big block car?

[bertfam]

Roger, you asked this same question over on the Team Camaro site, but you never got back to me.

http://www.camaros.net/forums/showthread.php?t=200503

Ed