I would be using my Traditions Lightning bolt with 28" barrel that is topped with a Bushnell Banner 3-9X40 scope. The gun shoots the 300gr Shockwave Bonded bullts well with 100 gr Loose of Pyrodex RS using a 209 Remington Kleenbore primer. I have taken many deer with this gun and I feel good with this one.
Key factors in choosing
1. You know you have one shot so use your best trouble-free gun.
2. You said you have timber and a clear area to shoot so pick one that can shoot through it.
This gun does it so I picked this one.