Thanks for your analysis Kim.
I initially started the angling of the engine using washers, three of them however there appeared to be no noticeable changes in downward thrust angle. This caused an increase in spacers one at a time until six (6). Using six (6) washers on the two top stand offs and one (1) each on the bottom two stand offs with blind nuts to secure the engine with socket screws, "8-32", I noticed the screws and blind nuts would stripe every time the engine is removed. Having all four at the same angle would prevent stripping and hence the reason this setup was applied.
One inch outer diameter washers with the hole small enough to insert an 8-32 socket screw is a good suggestion to use to spread the load on the firewall from the stand offs and will get a few of these from my local ace hardware store.
Engine pictured in above posts is an OS FF-320 Pegasus with 53ccm of engine displacement. Weighs in at a little over 5 pounds with onboard starter motor and starter ring gear to turn the prop shaft for starting.