I do not own any Tannenbaum products and can not answer as to whether or not they will work on G8, but if you read the comments about the outfit you mentioned, someone was able to get it to work on GN3 characters and that makes it think it is possible to get it to work on G8. The one thing that I do when using M4/V4 characters on G8 characters is put the G8 character in a T-pose prior to adding the clothing and with various scripts I own I am able to get the clothing to fit. The T-pose mainly helps with getting pants to properly fit the legs. This product is also good for fitting clothing - https://www.daz3d.com/sy-victoria-4-and-michael-4-clones-for-genesis-8.   If you do not have the SY clones and templates, I recommend that you get them because they are truly helpful with getting older model clothing to fit the newer models. I have some older model military outfits that I will render and upload to my gallery with the links to them posted in this thread.