Thanks for all the input, here is what Comp and Crane said:
Comp says to go with the XE250H, Crane says to go with the H-256-2 which now replaces the H-260-2 or the Z-268-2. Now they all say "smooth idle, good mileage, good low end torque, for towing and heavy duty". Fine. Now I know that. But there are differences in durations and differences in LCA and differences in lift, so surely that must make a difference somehwhere or do you think the difference netween these three cams won't show up in an engine? Then why should there be so many to choose from?
I think for a start I'm going to get a Desktop dyno (I have time at them moment) and test a few little changes. I don't have the possibility to test the final combination on a real dyno, so the work will be in planning it right first time (very easy job )
But please keep me informed on any new combinations or cam choices you've made, here in Germany there aren't so many people who really know very much about SBCs
Keep up the good work,
Max