The Hobbico Mains work fine. Just use the screws to adjust out the play. The Hobbico nose is a tragedy. I would look at Robart mechanicals. They look to have a good belly mount type nose gear.
As to engines, the recommended O.S. .55AX on a pipe pulls it around pretty well. But you could obviously go with a lot of others. I would not recommend a rear exhaust. The plane flies better with an underslung pipe. The pipe down the side hurts the left rudder knife edge.