display tuplet ratio in \rhythm markup

[damianlegassick]

Hi allin the following, is there any way to have the metric modulation markup via \rhythm 
show the ratio '5:7' instead of just '5'? I've tried \override TupletNumber.text = 
#tuplet-number::calc-fraction-text in various places but no joy.thanks, D\version 
"2.25.2" {  \time 7/8  \tuplet 5/7 {c'8 8 8 8 8}  \time 2/8  c'16 16 16 16  
\tempo \markup { \rhythm {\tuplet 5/7 {8}} = \rhythm {8}}  \time 2/4  c'8 8 8 8}