The easy way, without getting fancy, is to obtain a couple of 3/4" wide blocks of maple cut to the length you need for the engine standoff distance. Those maple blocks have to be about 1/4" to 1/2" wider than the distance between two engine mounting lugs. That's 1/4" to 1/2" to each side of the engine. Basically you now have a pair of 3/4" thick maple blocks that extend 1/4" to 1/2" past each side of the engine mounting holes, and as deep as the required standoff distance. Place one block so in spans a pair of engine mounting holes and mark the 3/4" width for the hole centers. Do the same for the other pair of engine mounting holes. You now have a pair of solid maple engine mounting blocks. Getting fancy and making them lighter is only a matter of cutting away anything on them that you determine you don't need or serves no purpose regarding rigidity. Total spent: about $2.00. They last forever.