Love to see you're working on an old Falcon coupe, those cars are hard to come by, most of them were shipped overseas for Mad Max Interceptor projects....
Mate, saw a heavy duty trolley at hardware store. If you make that centre wheel a larger heavy duty castor than the others it will give you tremendous manoeuvrability. It will the sit on either front three or rear three depending on which way you’re going.
Better being a little longer,you could make it so the engine mounts slip into the tubes and then you can use it for many different engines of various sizes etc....... Think I might make one myself-great design mate👍