Channel Balance Series 710 H-R40-48x84

I'm trying to replace my channel balances. The label on the window frame reads "Series 710 H-R40-48x84".
The channel balance on the right side (viewed from the inside of the house) is stamped 27-3 as seen in the picture. The left balance is too damaged to read the stamp but it appears it might say 27-4, but I'm not sure. I've enclosed pictures of the top and bottom of the balance. The metal portion of the balance measures 28 inches and is 9/16" wide.
Is the correct replacement S710-28? if so I'm not sure which option to choose. Do I weigh the sash and choose the correct weight range? Also, I'm replacing both balances, are the left and right balances identical or do I specify left and right when ordering?

Yes. The bottom appears to be a 15-001, and I believe the top is a 19-005.

OK, so you think the Channel stamp of 2730 is the appropriate choice even thought the actual stamp says 27-3?
Also, you recommend S395 as the base series. I'm enclosing a picture of the label on the window sill that shows "series: 710SH". Is S395 the correct base series?