yeah, that'll just drop every 6th frame.
it's a tall order converting 29.98 to 25.
you could try compressor,
go into the frame controls pane, and set retiming to "best"
maybe do a test on minute or so to see:
A: how long it takes, and B: is it worth it?
you might need to take it somewhere that can run it through a Terranex converter unit.
nick