'50s MOPAR Hemi question

[Tedscj at aol.com]

This isn't really EFI related, but can anyone point me to detailed 
information on '50s Mopar information?  My Web searches are only turning up 
'60s info.

Specifically, I found a '57 Dodge Custom Royal with a 325 Hemi and a single 
4bbl for sale fairly cheap.  I'm trying to find out if that makes it the D500 
option or if ALL Royal Customs came with Hemis.  If it had the dual 4bbl 
motor, then I'd be sure it was a D500 but it's only a single four which 
leaves me confused.
The serial # on the motor was KD500-1151 which IS a Dodge Hemi motor for the 
57 model year.  I just don't know if this makes the CAR a D500 which 
seriously affects it's value.

Thanks for any direction to the info.
Ted