It will physically fit between the towers, will need to enlarge the gearbox tunnel. All the small block Fords are 90 degree motors, despite some poeple trying to say the Windsor is 60 degrees. For legality I am not 100% on Oz laws but my understanding is the only way you will get it legal is as an individually constructed vehicle (ICV) which is an absolute nightmare. If you were really serious about doing it you would be better to move to NZ, most of the ones you see getting around in Oz are either dodgy or were converted years ago so have retained their legality under older rules.
Callum