Looking good Tim! One thing about the plastic clunk tanks, is that they can be very versatile. With a little planning and vision, you can set it up as a regular suction tank or uniflow, and be able to switch it from pressure to vent to atmosphere and anything in between. Make sure you have the engine well broken in just to eliminate any issues there. Set the tank up with the fuel pick up about even with the center of the bypass port on the engine as it sits in the profile configuration, or about 1/2" above the engine center line. That will put you close on how it will run upright and inverted, and you can fine tune by just twisting the stopper to raise and lower the pick up. Making sure everything is straight, even and in adjustment before first flights is called "bench trim." As you gain experience and learn more, you can bench trim a model to be close enough in flight trim to do the pattern or most of it on the first flight! That does come with time and experience, and is the direct result of paying attention to details on every model you build and fly.
Good luck and have fun!
MERRY CHRISTMAS and HAPPY NEW YEAR!
Dan McEntee
PS to Add: I was just looking at the photo of your airplane and noticed the needle valve sticking way up above the nose. If that is a Super Tiger type needle valve, cut the length down to where it is flush with the top of the nose. This does two things: 1) when the needle is that long and unsupported, it can act like a tuning fork and make for some weird runs. You can not tighten the collet enough to fix it. I cut them down and rebend them, or solder some sort of knob like a small nut onto the end of the needle. 2) The other thing cutting it down does is it keeps it from being broken off in the event of an inverted landing of any kind, and you WILL experience those, so might as well plan for it. If the needle doesn't get caught and broken on the inverted landing, most times you can just clean the airplane up of debris and fly again right away. It's no fun throwing a whole needle valve assembly away just because the needle broke and it's stuck in the spray bar! Been there and done that a LOT!