Hi,
Used to own a Puma myself.
I think the 1.6 Zetec SE from the Focus also appeared in the Puma, when the 1.4 Puma was stopped.
so you could drop a 1.6 unit in the Puma with little effort.
read this:
http://en.wikipedia.org/wiki/Ford_Zetec_engine
sorry if this isn't much help!
Car killer - the 1.4 Zetec SE appears in the MK1 focus 1.4CL I think!