Your marlin model 782 was made by marlin in 1980.You can find this by subtracting the first 2 digits from 100.Hence 100-20=80(1980).
Your serial number indicates that your Marlin model 782 was made in the year 1977.
Your Marlin model 783 was made in the year 1971.
You will need to add the serial number,to get the answer to your question.
150$ to 250$ is my best guess
11238344
Your serial number indicates that your model 782 rifle was made in the year 1981.
My Glenfield Model 25 has a micro-groove barrel,so I imagine others do as well.
$350-400 in PERFECT shape.
50-200
What is the value of a Marlin Micro Groove Barrel MCD 336 Cal 30-30 WIN?"
1987
It should be marked on the barrel if it has the Marlin micro groove rifling.The model 25m was made from 1989-2003.That being said it will if it was a early made rifle.