340 crank- standard or reverse rotation?

I wonder what the firing order would be; 1-3-4-8-6-2-7-5?

No it's simply the same firing order read backwards, IE 27563481

Then put the 1 in front as that's what you start with so it's 12756348

This is chev, same thing. NOTE In the marine world, "LH rotation" is "normal car" so "RH rotation" is reversed from automotive