The 77027 zip is correct for that year. Check W's released personal records. He provided the address with that zip code. The 77056 post office may have been added later, and the boundaries changed with population growth.
Ok, and if I jumped too hard on Montrose, I'm sorry. I'm trying to find some documentation online to show when 056 was established. No luck so far.
Occasionally the US Postal Service® will add new or realign existing ZIP Code™ areas to accommodate population growth. New ZIP Codes are released by the District Office approximately 30 days before the ZIP Code change goes into effect. Most large mailers (i.e., credit card or utility companies) subscribe to US Postal Service products that will reflect the ZIP Code change within three to six months from the effective date. Friends, family and smaller businesses will have to be notified individually. Mail with the old ZIP Code will continue to be delivered for one year.Well, so much for that great discovery. Can I get some of that crow over here? :(