...the shore should be around 70 ish. Also, how well does it bond to metal, and can I treat the metal with a product to increase the adhesion?
Most commonly motor mounts (engine bushes) are made using something more like an 80 or 90 shore resin. In fact our PX90 has been used by a number of customers to create engine mounts.
If you're confident that you do need a 70 shore for your application then our closest shore hardness would be our PX60 but my opinion is that this would be too soft for most typical engine mount applications.
As for the bond to metal, we don't really have, and you shouldn't really need, an adhesion promoter for PU to aluminium - they should bond well. As usual, just make sure the surface is clean, completely grease-free (using acetone) and lightly keyed (using abrasive paper).