Having both solid mounts is pretty harsh on a street car, been there done that.

There are a few options.

You could install a solid mount on the drivers(torque) side and leave the rubber on the passenger side.
or
I would check your current mounts to see if they aren't broken or badly worn and replace if needed, then add one of these.

http://www.engine-swaps.com/Pages/ProductsType/TorqueStraps.html#head4



Or if you want to do it on the cheap just get a strong small section of chain.