If you wanted to prove out the other genes, you could consider breeding him to something with only a visual recessive like clown or DG. Then all babies will be fire het for a recessive and any other genes are from dad.
Otherwise you could always go with something else allelic so you have 2 visual genes guaranteed in the hatchlings. Maybe something in the BlueEL complex or a highway or ivory.
Enchi could also be a good gene in the mix if the cinny does prove out.
But the biggest question is more along the lines of, “What would you like to produce?” Because of you have a morph you want to work towards, none of this may help
Look for what you want to produce. Look around on MM with fire in the mix and find something you want and work towards it. However, the market is very over-saturated right now and those are all common genes. Be prepared to hold onto hatchlings for months or even longer.