As mentioned, draw length and the resulting poundage at that draw is critical in determining the correct arrow choice.
Just a guess, but I would recommend the Easton Epic .600 spine. They won't be too heavy, as they are only 7.3 gpi bareshaft and will finish out around 375-425 gr. using 125-175 gr. points, depending on finished length and point weight. (9.5-10.5 gpp)
The Heritage 90's (.530 spine) are 9.4 gpi and will finish out around 435-485 grains using 125-175 gr. points. (11-12.0 gpp)
Problem with the Heritage 90 is that if you need more weight upfront to get correct dynamic spine (probably so, since they are stiffer than a .600), they will be even heavier. But of course, if the longbow is a straight-limbed bow, the extra arrow weight might make the bow more enjoyable to shoot (they like heavy arrows).
If in fact your wife will be shooting 41 pounds at her draw, I think you will have an easy time with the 600's. I shoot them out of different kinds of bows that are between 40-45# with 28"-30" arrows and various point weights.
Have fun!
- Dave