Digital BW, The Print

I've been using the UT-14 inkset in a Epson 1400.  I'm going to switch out the two cool tone 
PK and LK in the C and LC positions using the HP PK in the C position and a dilute of HP PK & 
glop in the LC position.

Do I need to flush the heads with cleaning cartridges or should a simple purge with the new 
inks be sufficient?

Thanks,
Randy