I just looked at the manual starting about p.16, and it sounds like you're doing it right. No need for the 1" hole though, since you already have holes drilled for both fuel lines. I'd say it's good. Also, the big hole locks in the tank height, so you lose the option of changing its height later.  The firewall can experience a fair amount of fuel soak in its life, so maintaining its fuel proof integrity is important. The fewer/smaller holes present, the better. <div>
</div><div>Placing closed-cell foam all around the tank is recommended to minimize fuel foaming and thus a lean run. Just don't pack it tight, a little play is fine and makes it easy to remove for repairs and checks. I've also secured the rear of the tank with a piece of hard balsa stick placed diagonally just ahead of the former, then turned/wedged as needed. You can tack it with CA lightly, again keeping in mind the option to pop the piece out to gain access to the tank. </div><div>
</div><div>These are all ideas from everyone here, hopefully you get several to look through and decide what seems best for your application. There's more than one way to skin that cat!</div>