Hi there,
Unfortunately I do not have a CAD drawing of a Lycoming IO-540, but I would like to get one too. Any information regarding the engine mount type, or better a copy of a Lycoming "installation" drawing will be highly appreciated. I am looking forward to design an airplane with AEIO-540 L1B5D and actually built several 3D parts of it in Rhino, but the model is far from complete.
It may not be relevant in this thread, however I can offer a Rhino model of a Lycoming O-320 E2D that I built and used it to design the firewall forward layout of my previous project. I mean, it is good enough to verify your cowlings, baffles, ducting, engine mount, exhaust and engine controls routing.
Cheers,