Try it with some loose shims under the flats on the trigger assembly. If that draws it down into the receiver glue some permanent hardwood shims in the wood. Stain to match. Popsicle sticks are birch.
If it takes pressure to pull the rear down that is ok within reason. You’re springing the barrel from the front ferrule which is good for accuracy and what is supposed to happen by design.
ETA the handguard were all fiberglass. No wood ones to match the stock except aftermarket. The glass ones let the barrel cool better.
I have a box of handguard some where. They’re not shiny and may have minor strain cracks. No bands came with them but I have a dozen or so like that. You can haz one for shipping. They’re suitable as is or better with a fresh coat of ugly brown paint. They’re not the premium shiny smooth brown SAInc used for years but they’re genuine usgi.