Hmmm. Interesting. As I recall, the tank in the Oscar was two premolded, hard, clear plastic pieces that were heat-sealed together around the horizontal centerline. It had plastic "straws" coming out of it for standard over-n-under venting. I don't think I used it(?), so it might still be in the kit box. There were also two pieces of shiny metal sheet that must have been for landing gear doors? The Oscar was fully planked so I didn't get/use any covering. But as a kid, planking that whole thing and making it look nice was a bit of a challenge. I would think the Fox .15 would pull it just fine. I recently ran one on a Magician 15 and it had more than enough umph! For those that may not have figured out the translation, the "powdered bones" was what you mixed with water to make the glue. I think I just bought what the guys in the hobby shop called a "gloob-a-two." Almost certainly a tube of Ambroid given the era.
Fun memories. Hope you enjoy building one of yours,
Dave