John, for someone that was worried about their skills you did better than most that would feel they didn't need any advice. That looks lovely.

My only suggestion is to leave the wood block a lot thicker than 1/4 inch. And in fact for durability against any nasty landings and given that many of our models often need nose weight anyway you might want to consider leaving it solid. In particular if you started with a block that was softer and lighter.

If you hollow it at all maybe it would be just to add any additional nose weight. So given all this I'd suggest that you leave the block only tacked in place for now. Finish off the model and cover the wings and tail. Place the components and check for balance. Then bust the tack glue spots and depending on any weight trim either just glue the block on as solid or hollow it to lighten or hollow to allow placing the lion's share of any ballast you need. THEN glue it into position permanently and cover the fuselage for a seamless look.

If you have access to the rear of the block through the nose bulkhead via the nose gear well you might also consider a small hollowed area and a plug in the plywood bulkhead to allow you to feed in and remove some lead shot as an aid for final trimming with flight testing. After all the further forward it is the less you need.