DO NOT run a Champion spark plug!! I have had them seize in the head, ruining the threads requiring a hell coil type repair. I have also had the ceramic insulator break, ruining the piston & cylinder. I would recommend a NGK, I use CMR7H. If you run a hard tank, it must be vented. The Walbro (& other) carbs on our gassers have a fuel pump, so you can run a bladder style fuel system with no venting needed. Believe it or not, a Baxter IV bag is an excellent fuel cell. Single tygon line with a T fitting for refueling, although you will need to reverse your fuel pump to eliminate air. Fill nearly full, reverse to remove air, then fill completely. The bags will harden over time, & need replacing so acessability is a consideration. I get about a season out of a bag, with regular use. Sitting unused seems to harden them sooner. If not being used regularly/ say, weekly - purge any air often - air in the bag will harden them sooner than solid fuel. VERY common fuel system on RC gas boats, check out Jim's RC Boat Dock (JRCBD) or Model Gas Boats for examples & Gizmo Motors or Zippkits for supplies. Inexpensive, simple & solid fuel with no clunk to set up. A flat plywood tray where the tank sits with a couple cup hooks for rubber bands to hold the bag in place, & some thin foam sheet to eliminate chafing. I would also recommend using an oil spec'd for air cooled engines. TCW3 oils for water cooled engines are designed for lower temps & will not perform well, resulting in possible engine damage or failure.