My beloved Scott Spark 20 with an all carbon frame bit the dust after many years. I would like a new bike to rise out of the ashes of the spark and have seen a 2nd had Alpine 160 frame I fancy. Is this a good match though, the Spark has 120mm travel forks and I guess the Alpine has 160mm rear travel, would that make for a badly handling bike?
They are not even vaguely comparable.
The Scott Spark is a short travel XC bike, and the Orange Alpine is a big burly enduro bike.
An enduro bike will need a longer fork as a bare minimum, but even if you move over the rest of your components, will not behave anything like an XC bike in terms of pedalling or handling.
I ride a Spark 20 - If original forks and shock, they will be close to end of life - not worth spending too much effort trying to reuse them. Drive train, unless reasonably recently replaced, is probably not worth saving, leaving wheels and tires.
If you like the bike, your best option would be get a flogged out XC bike (Ideally a Spark) of similar vintage as a donor bike. If not a spark - look for a frame that takes a 165/38 rear shock, unless you know the shock on the donor frame is in good nick, you need to match axles, steerer type and rear shock. FD mount and BB are also bits that might not swap.
Economically, its probably not worth doing it, Spark 20 is 26" wheels and 10 year old geometry. I recently bought my son a Merida OneTwenty 500 - an entry level $US1200 bike. In many ways its a better bike to ride than my Carbon Spark.