IMO, with test arrows it is best to have the exact spine marked on the shaft, not just a range. A decent set of test arrows will have spines with 2 lb spacing; 3 lb max. 50-55 is 6 lbs and marked with a range, you never really know what spine you are shooting. 50-55 and 55-60 can both have 55 lb spine arrows. It can make getting good results confusing.
A good set of test arrows is one of the best investments and tools a wood arrow shooter can have.
Babs, what range do you think you will need?