Imperial first started making knives in 1917. They were the world largest knife making company by 1940 (often making 100,000 knives per day!). They are still in operation today producing their Schrade name brand.
Values tend to be low to medium - but values on switch blade have been tricky since 1958 (generally higher but depends on ability to legally own within state - also never mail them). Be careful with the older knife patterns, some of the early auto-open paterns can be worth several hundred dollars. Its often better to keep the worn spring on an otherwise minty knife then to replace it and damage the knife collector value.
If the knife is in otherwise good condition and if it it legal to own in your state I would suggest that you show it to some of your local dealers before making any modifications.