andyl, We would all love to have 427ci but the reality is that with modern alloy heads and cams on/in Windsor based engines one can enjoy the cobra experience especially if one stroked the windsor.
The W302/5ltr stroked to 331/347 makes a great engine with say AFR heads and the 351W is bluddy fantastic as a 392/408ci with the same heads.
My preferred engine would be a 351 based clevor. A 351 windsor with CHI 3V alloy heads and a nice roller cam and aftermarket 4 barrel FI.
Don't tell any-one I said that ... I'd never live it down
