If it is the "Giant" Stinger, with the 84" wingspan, you do not need to shorten the nose. The model is designed for a gasser.
I built one several years ago (about 7 or so), and powered it with a Sachs 4.2, then we put on a friends D&B 3.7 twin. Later used it to put some run time on his G-62, and my Saito 270. I then gave it to another flyer who has been flying it with a G-62 also. Looks like I will be getting it back so I will be putting the 4.2 back on it.
Do be sure and run fuse doublers from the firewall, the trailing edge of the wing. The L/E cutout in the fuse is a weak point, and the fuse will eventually break there.