Wery nice round trip. You should drive to of Aavasaksa hill. Aavasaksa to Pello best salmon river and nice places to brake time.
Start from either end. Enjoy the views at Pallas, eat or get refreshments and start your journey towards Hetta. Stop at the center small cafe pub (dont let the appearance fool you) and eat an Gurppa-burger with raindeer. (watch out for the wildlife)
nice daytrip stop for lunch in Kemijärvi and for coffee in Auttin Kyläkievari