I made my own when I did my engine swap on my 310.
You will need to go to a auto parts store and buy a couple caulking tubes of "window weld". It is a Urethane adhesive that is used to glue windshields in, and is resistant to petroleum. Dont confuse it with black RTV silicone. Not the same. This stuff is tough as nails
You will need to remove the old rubber mounts, but you will need to save the big steel washers and bolt sleeves. If you dont have the engine and mounting plate removed, do that now. reassemble the mounts to the engine with washers and sleeves on the engine plate as if it where mounted with the original rubber mounts. Find something to use as spacers to center up the mounts in the plate. Equal distance top/bottom. Now find a cardboard tube that will fits snugly over the large washers to create a cavity. Drill a hole in the cardboard sleeves(1/4") and slide them onto the bottom washers.
The Urethane adhesive is moisture/atmosphere activated. Meaning, once you open it you must be dedicated to using it. The entire tube will cure, so only break the seal when you are ready to use it.
Once you have the cardboard sleeves on and the mounts where you want them, break the seal on the tube of sealant and begin filling the mounts from the bottom up. Push it through the hole you drilled in the card board tube until it comes out the top and forms a uniform "mushroom" appearance on the top. Basicly, make it look like a engine mount. You will need to let it sit for a couple days to cure. Needs to be above 50 deg F as well. Once it cures, its there for good. Meaning, dont screw up or its hell to remove.