My 418 doesn't seem want much different jetting than the 340. It's a 6-pack, but the jetting is almost identical. Considerably smaller than what you are talking about. Would be interesting to see where you end up at.
will post back when i get it worked out. i have a big list of stuff to do.. just no motivation. the cold just really shuts me down now. I wanna pull my interior and fix some stuff.. alignment.. new front wheel studs, new engine.. go through the trans for some upgrades.. umm and like 10 other things i'm forgetting :)
Rignt now i am just keeping it together so i can still drive it if i feel like it..
Most of the stuff i wanna do aren't really long jobs. just need to get to it..
The 318 actually runs really good.. but the bottom end was just a $300 facebook thing to get it running.. no weird noises but the cam bearings are... questionable :) very flakey