Sounds good...You do realise that X'ing with LR wont ensure your new strain is autoflowering or even short for that matter? That requires selective breeding,crossing and back crossing..
If your aim is for a stronger auto strain, why not x some of the other autos that are already out there, like auto-ak X auto white russian etc.
I'd imagine that your the auto trait would be quite high in X's like that, and you'd get some of the qualities of each plants