The main thing you need to realize about build sheets and many other paper products from that period is that the chemistry used in the paper making (pulping) process was acidic. At the time acid was the cheapest easiest way to break the fibers down, the archival implications were not fully realized until later and by that time the process was changed to a more neutral / basic process.
The acidic nature of the pulping process is what causes old newspapers to turn yellow and begin deteriorating. The best solution would be to take it to someone who specializes in old books (most towns have some one like this) they will be able to stabilize the paper by nuetralizing the acid in the paper with different chemicals.
Then they will tell you the same thing... keep it out of the sun... mount it using non acidic archival mounts behind glass with a UV filter on the glass.