Why would a tekin esc have to use old style batteries.
If it uses 5cell Ni** or less then yes,
But 6cell Ni** = 8.4V 2s LiPO = 8.4V charged.
Just because something is old doesn't mean you can't run newer technology, with LiPO you need some sort of LVD which is why manufacturers state not to use LiPO on esc's that doesn't have this feature, But you can buy these separately.
You may need to power the Rx with a different supply but that shouldn't be a problem