You do realize that with stock springs in a SOA setup, there is no way you are going to run 38's on that 60. You will need a much larger lift spring and then SOA to fit those.
Just out of curiosity, why the hell do you want to run 38's? You want to do a diesel conversion right? I have read your posts and you have posted on my thread (my Cummins 4BT conversion) about how you want to do a diesel conversion.
I also remember that you want to run up mountain passes at 70mph towing a snow mobile trailer. Now, realistically speaking, do you think this is a good idea? I am not saying it can't be done but you are really going to have to tweak a diesel motor to do what you want to do.
FWIW, I have my 60 sprung over. I love it, the ride is great and I have an adjustable shock that I can tweak to stiffen or loosen the ride.
I would not recommend the OME heavy duty springs. they are for serious expedition use for carrying heavy loads all the time. they ride like s*** when there is no weight on them. Trust me, they are a bone jarring experience.
Why do you feel that it is necessary to run a heavy duty spring? What do you plan on carrying?
If you are interested in a set of flat 60 springs that are in good shape, PM. I have a set that I should get rid of.
Also, where do you plan on going with 38's that you can't get to with 35's? 60's are not a great rig for rock crawling. They are too heavy and the rear over hang is too long. Unless, you plan on bobbing it, I would stay with 35's and call it good.