The RCGF 26cc should be fine. I have one in a 120 size Pilatus Porter (about 14 lb all up weight) where it is fine. My advice is to use an electric starter (any typical gloplug starter is fine), as it can take a while to get the fuel to the carby on the first start for the morning.
I was a bit worried that the Pt-19 cowl might not provide enough cooling (in terms of the size of the exit vent), but it is fine. I was tempted to go the RCGF route (the engines are so cheap), but had a spare ASP 120 4-stroke sitting around and decided to use this.
There are some photos of my stock plane if you click 'gallery' at the left bottom of this message.
I has some more flights on the weekend which went well. As I previously noted, the flaps really slow it up for landing, but you want to try to land at about 10km/hr to reduce bouncing and bending back the undercarraige wire to which the oleos clamp. The wires are easy enough to bend back to their position aftera bad landing.
This is a war plane, albiet a mild mannered one,Â*so getting the CoG right is essential for maiden. The plan will tip stall and would be a bugger to recover from a spin if you don't catch it straight away. Set both aerollins about 4mm up from flush will minimise the risks of tip stall (it effectively raises the stall speed of the wing tip a little, so that it is closer to the root of the wing which allows a few km slower flight before stall, and also gives a more benign stall).
Mine looks and sounds fantastic in the air with the 4-stroke ASP. Personally, I don't much like the sound of the RCGF. You can improve it by glueing some foam on the inside surfaces of the cowl (making sure not to interfere with the air flow), wrapping some 'Rescue Tape' around the muffler (this is a good quality silicon tape that withstands heat and muffles the sound somewhat) and using a decent wooden propellor.