Cannon Fodder,
Check back to this post for any info I have for you.
How about some photos of your Spencer? Low serial #, got to see some photos of it!
The closest two matches (before and after) your Spencer Rifle serial # 8087 are:
Spencer Rifle serial # 8063 issued to a member of Co. K 97th Indiana Volunteer Infantry on or about 04-08-1865; and
Spencer rifle serial # 8120 issued to a member of Co. G 8th Indiana Volunteer Cavalry on or about 04-08-1865.
Best I can give you,
Two Flints