You could head up to Hurstwood reservoir, from there you have various route options over and into Hebden bridge, easy to make a godo 4 to 4.5 hour ride.
Up from Hurstwood to the windmills, join the long causeway heading hebden direction for a bit. Down delph lane, past Todmorden golf course some good DH options down to the main road, climb up round the back of stoodley pike, descend back trhough callis wood to hebden.
Climb up midgehole but fork right to peckets well, down peckets well descent optional right at hardcastle crags, climb up to the calderway back over towards Widdop. Up and over widdop, nice steady descent back into Hurstwood. Would be around 28/32 miles dependant on options around Stoodley and around 2800/3100ft climbing.
You may be able to do most of the MTL dependant on speed. If you cut out the walsden/rooley moor climb bits and cut from Todmorden directly over towards Bacup and towards the deerplay, youll cut out 8/10 miles and safely do it in your time frame.