I have one, Quite easy to do in fact. Go to Numerich's site and you can pick up a schematic of the 87A on there. Kinda cool is that my 87A came from my Grandfather as well. It was purchased some time in the mid-40's I believe.
1) loosen the large machine screw on the bottom of the for-stock. (you can remove it if you want to refinish the stock)
2) butt plate comes off with 2 screws
3) trigger guard comes off with 2 screws
That does it for the stock.
Action:
1) there is a large 'nut' on the rear of the action that you unscrew in order to remove the springs, bolt, and such. You will need to fiddle with the trigger to get the works to come out. Remove the lock handle from the bolt once you get the firing pin out. You CANNOT remove the lock handle from the bolt until the firing pin comes out the back.
2) Once the springs and bolt carrier are out, remove the bolt lock/cocking handle.
3) push the bolt backwards, you will need to fiddle with the trigger again to get the bolt past the trigger mechanism.
That takes care of the internals.
1) safety is 2 small screws, if memory serves.
2) trigger assembly is also 2 small'ish screws.
If you get to a point take a pick and let me know. I will help you out along the way. This will at least get the gun to a point where you can do a good cleaning and inspection. My 87A went through a house fire and it has refinished just fine so far.
I media blasted the entire metal works. Then cleaned and oiled what needed it. DO NOT media blast the bolt/carrier/spring assemblies. Worst case you can order new replacement parts from Numerich online. Parts are inexpensive and they ship to Canada no problem. These old guns are remarkably sturdy and reliable. I just had mine out last week for the first time testing it on semi-auto. Worked like a dream, accurate as all get out at 25 yards with bad iron sites as well.
Like I said before, feel free to pm or e-mail me with questions and I will gladly help out another 87A guy any day.