I ran 4:08:35 last year, and was happy with my pacing other than a slow ascent of Ingleborough due to cramp, and a slow last mile or so. Having said that I took a load of places on the first part of the IngleB descent - maybe I shouldn't have gone quite so fast there!

I agree with the comments about making a fairly slow start. My suggestion would be to base your target pace on the splits of someone who finished in about your target time, but who ran a fairly slow first half. It's easier said than done though!

Also, come and run the Edale Skyline on 30th March - similar distance, similar total climb, not so much road though.