do not be tempyed to put it in a pastic document hole punched wallet, they change their flexibility over time and could damage it. Most conservators would avid handling a document, store it in an airtight box in a dry place. Record Offices would keep thinsg simple and obviously the less handling the better, i have laminated some original irreplacable documents, but it is quite a modern process and noone can really guage yet the longevity of anything laminated. There are certain papers on the market that have in excess of 100 years life in theory. If you ever visit a record office and request an item fropm the catalogue that is a few hundred years old, any deteriation in the paper and ink has occurred before being deposited, and so it is really down to the care shown during the time it is in your possession.
I think any good conservator in your local recotd office would be able to give you the best advice.