.
The information is not that hard to find if you look.
There are tons of links when doing Google searchs.
These links are from the Remington site and give the dates for the Sportsman 78 and the "Kit guns".
http://www.remington.com/products/archi ... tsman.aspx
http://www.remington.com/products/archi ... l-700.aspx
Just because it "looks like" (or has some of the characteristics of) a Sportsman 78 with Model 700 on the receiver, doesn't mean it isn't just a variation of a Model 700 ADL. The number of variations Remington put together in the lifetimes of these guns is astronomical.
FIRST......look at the barrel date code and determine what month/year it was made.
That will help you rule some options in or out.
http://www.remingtonsociety.com/rsa/que ... arrelcodes
Den