I am about to start a modified(*) 12wk/55mpw program by Pfitzinger after this recovery week from the last Sunday half. I have used his 24wk/55mpw successfuly before and also his 18wk/<40mpw (from Road Racing for Serious Runners) not so successfully. So this will be my 3rd full.
(* modifed to make it 15wk long. Plus, one or even two recovery runs will be replaced by bike/swim.)
A few qusetions regarding setting up training paces;
(1) LT run: Should I use the result of this half to establish LT run? It wasn't perfectly executed half due to a calf cramp during the last 2 miles. The ave pace was 7:41 (prior to cramp was 7;36ish). Or 10K (5 weeks ago) pace (7:09) + 15sec (=7:24) is more benefitial? Or should I stick with the LT HR (= 171, was tested back in March 07 during a training for Boston), regardless of the pace? My LT pace during this half training was mostly based on HR. But I think my LT HR increased during this half training cycle.
(2) Long run: Based on the half time, the predictors say anywhere from 8:00pace to 8:10pace marathon I may be able to capable of running. Do I need to even worry about specific MP at this early stage of training? Or just put in miles, staying withint "MP+20%~10%" guideline? At what point do you nail the target MP? At one of the 'marathon pace specific run'? BTW 12wk program has only one of those (15 w/12@MP).

For my first maraton for which I used 24wk/55mpw, my target MP was much slower than what the predictors said, because I simply wanted to BQ. Now I want to see what I can do while staying away from injuries. I am not sure if I make 8:00~8:10 as a goal MP or stay much conservative because of low weekly mileage and being somewhat injury prone. I ran about 25~30mpw for the half if that means anything.

Thanks for your advice. I am excited about starting a marathon training... again.