For the chimney....
I took a piece of roof flashing, rolled a bit into a tube
that fits the engine top, epoxied it and taped it to hold
till the epoxy hardens. Paint it as you see fit, mine is
black with a bit of gold paint at the top. It is 1 3/4"
tall, a length that seemed proportional with the engine.
I like the way it looks, even without a topper!
Good Luck,
Wayne