I havent heard of any one putting a v6 into a puma/fiesta your looking at big bucks there, also as stated above the weight distrbution will be all to cock it will handle like shit, but its up to you m8.
There are alot of better options from my point of view/experience of the moddin scene :- silver top 2ltr zetec (bit old now), black top 2ltr zetec (better but heavy due to its cast iron block) also with the 2ltr zetec you can go for the st170 engine or even rs engine if your looking for a turbo, 2ltr or even better 2.3ltr duretec (much better choice ali block, head etc lightness is the key to these cars)
with the zetec's you can either use a fiesta diesel gear box (with 1.7 internals) or its orig gear box which will fit. but with the duretec you have to use the orig gear box as nothing in the ford range will fit.
with the above options you will have little problems fitting or sourcing the parts to do so and will piss all over 250bhp with good torque with just cams anf throttle bodies.
but
i have a 1.6 zs which is tuned to 160, i am refurbing a 1.7 to transfer the bits over to (practically the same block) with a few extra bits im going to be just under the 200bhp mark, no turbo no superchargers just good old na.
As they say, the choice is up to you m8