Honestly, neither. The Revell 1/25 kit first came out in 1968 and is based on their earlier Bel Air kit. It hsa opening everything, but will take a lot of effort to get right. I'm slowly trying to get one built, but I've been trying to build one since it first came out. On the other hand is the Monogram 1/24 scale kit which came out in 1978. It's body is very badly proportioned, almost toy-like.
I did see someone combine the roof of the newer Revell/Monogram 1956 Nomad to the body of the new tool 1957 Chevy, but that would be alot of work.

Mark,

Thats very helpful information. Thank you for the reply.

—mike