RE: What engine?
The Phoenix Strega is a great little inexpensive ship that will fly well with anything from a good .46 and up. I have set them up with various .46, .61's and YS 110's. Currently just set up one with a Bar Stock Jett .91 on a Jett quarter wave pipe and another I just set up for myself with an OS .95AX. Tested that one along with the Jett engined ship just in the last week each day.
However if you are new to warbirds my first choice would be an OS .55AX. This will be a wonderful combination.
This airplane is my chief recomendation for a first warbird and/or warbird pylon racing.
John