RE: Do You have a better idea about cowl mounting blocks?
I have used this method on many, many planes and not a SINGLE failure in 10 years.
1> use good quality hardwood servo rails or engine mounting rail 3/4" x 3/4" x 1/2"
2> scuff the firewall with a dremel or 100 grit sandpaper (I even do this successfully on fiberglass firewalls, like on the lancair ES from GP) where the wood will attach. Prior to gluing - wipe with ALCOHOL (not thinner or acetone, both these leave petroleum residue that will weaken epoxy).
3> attach the mounts with 30 MIN epoxy (30 minute allows more working time and it is stronger)
4> test mount the cowl and then drill 1/16" holes into the hardwood blocks where the cowl attaches. Use small screws to hold the cowl in place while you drill all the holes, putting a screw into each new hole before drilling the next one.
5> take the cowl off. Drill the 1/16" holes out to 1/8" carefully. Press in a 1/2" long piece of Nyrod insert (yellow part)and use CA to set it.
6> mount the cowl and set the original screws into the nyrod. They will never come loose in flight and remain tight after many removals. If after many uses if they are not tight enough, simply drill out the nyrod and install a new one and re-ca. Simple and replaceable.
If you want a longer screw - servo mounting screws are perfect for this.
I have used this on 1/2a all the way up to 33%+ planes. It works well and every time.
DP