Your barrel must have a min. OD of at least .860 and a max. bore diameter of .745 (can be smaller however).. if these chokes will work.. I don't think the Remington barrels are that thick.. but if they are.. Stu Wright will do a fine job of installing the Invector plus tubes..
Joe--Since it is a 870 you could probably find another barrel to suit whatever needs you wanted to meet. The price of boring and threading will probably be similar in price to what a used barrel with chokes already installed. Just trying to offer options.
Thanks Matt -- I'm actually using a sportsman 58 TB for trap but have a 26" skeet which I plan on using for the local 5-stand. I'll just have to change barrels for the long shots. A "new to me" 870 barrel will require cutting gas holes as well. Oh well, its the price to shoot vintage guns. Joe