You are the man brother! Looks like you have put some serious thought into it!
I am only going on gut and years of coaching, but Id say go for broke with the Hdrol the old way you used to train and the way you preached to your buddys. Im not a guru on anabolics, so if there is something behind it that makes bodybuilding more appropriate while on assistance, then I guess my gut is wrong. However Ive always wondered how much gains dudes could make who are natural or not, doing bodybuilding wishing they would get bigger. Your going to increase your T&GH much more naturally with full body lifts, compound movements, complexes, etc the things you seem to have done in the past-ie training like an athlete. So in addition to the Hdrol, I would think you would make better gains not doing the bodybuilding thing. As far as cutting fat or weight, the full body lifts etc and interval training are going to burn far more calories then steady state "cardio", ie EPOC. I still shake my head when I see the magazines, the forums, and even a few friends in the bodybuilding/fitness world (pros BTW), that harp on "cardio cardio"....its very ignorant. Many times people are great because of genetics, chemistry, diet, mutliple variables, but NOT their training, actually in spite of their training.
Id take the look of a D-IA or Olympic level sprinter anyday over a bodybuilder, and they are doing training primarily of what you said you used to do, not bodybuilding. When it gets to splitting hairs of the best of the best genetics in the world from each country, you are not going to find too many olympic level power athletes doing any sort of bodybuilding or Crossfit type stuff. However, plenty of athletes look pretty freaky good in a bodybuilding way.
Ive tossed around doing some sort of bodybuilding workouts due to some health and hormone issues, but I am praying for the day I can get back on the platform and into the squat rack, back in a ring for some MMA, or back on a track for some speed and agility work.
No doubt if you are looking for specific hypertrophy in a particular area or bodypart, do some "bodybuilding", but Id play with doing it at the end of a full body or split athletic type workout. Again I do not claim to know much about bodybuilding, loved it growing up, huge fan...tried all the muscle magazine routines in middle school, high school and some even in college....looking back with what I know now from science and coaching hundreds of athletes, and my own training blunders and success, unless you are competing in bodybuilding, training like an athlete may allow more people to approach their goals initially then doing traditional commerical gym training. Id venture to say some people whose aim is bodybuilding, might be better off starting with some traditional powerlifting or olympic lifting type cycles for a year or two, with brief periods of hypertrophy training, cycling back into the powerlifting and olympic lifting. I do not know if you are old enough, but back in the day Franco Columbo was hanging with Arnold and the best of them (the squat segment in Pumping Iron used to make me go apesh$t), but also competed in powerlifting, the old school Worlds Strongest Man competitions, etc. Arnold even did some of the other "strongman" competitions that are lesser known with totally odd lifts back then. I know they are not as huge and ripped as the guys today, but seriously how many people go to that level, with those genetics, that ability to devote their life to, and the money and connections to be on all kinds of gear?
Ah Im rambling on a Friday night...food for thought guys.