I shoot a 60# compound, but I want to get a longbow in 55#. Do you think the arrows I use on my compound would work ona longbow?
I would probably use different broadhead, but my main thought is if the arrows will work.

I'd really doubt it. Your arrows for the compound would more then likely be overspined. Is this your first longbow? If so, and you are planning on using it on big game, I'd take a look at your state regulationsfor minimal poundages or the like. Then I'd look to get a trad bow in that area (for the first one). Here it is 40 pounds.

Here is a link to a pretty good spine chart for traditional bows:

http://www.arrowsbykelly.com/Spine_Charts.html

You do have to be careful when switching from wheels to sticks. You use different muscles for the two. I was just talking with a young man who switched from compound to recurve last year. He was shooting a 90# compound and bought a 72# recurve. He couldn't pull it back! I, on the other hand, easily shoot 3D tournaments with my 80# bows yet I can't drop over a 75# compound!