Does it have to be steel? I notice some of them for sale on the net for other motors are aluminum. If it's just to simlulate the bulging from the studs in the cylinders, it seems aluminum would work too. It's not like the plate is going to provide the exact same deformation as the heads anyway.
I was thinking about making my own torque plate if a local shop doesn't have one. It's basically a plate with clearance for studs, maybe .050 over on the cyl diameter, then have it double disk ground....(?)
Or am I off base?