OK this is going to a strange question…but in bodybuilding, if you felt that a certain bodybuilders proportions were the absolute ideal, could you take measuresments of the persons body, then adjust them to your own height (constraining the proportions) so you could plan measurement goals for each bodypart, with a goal of basically having the same bodytype, but shorter?
I’m not sure what you’re asking, here… Certainly, you can perform the calculations, and certainly you can set those measurements as your targets. Are you asking whether such measurements would be achievable (but then, they might not be even if you’re the same height), or whether they would represent a healthy physique for you (but then, they might not be healthy on the model bodybuilder, either, regardless of how it looked), or if it would look as good on you (if you truly matched all of the proportions, you would indeed look like a scaled version of the model)? Or something else?
You can certainly try, but there’s more to it than just height. If you’re an ectomorph and they’re an endomorph, or your tendons aren’t the same length as theirs, or your muscle bellies aren’t shaped like theirs, it ain’t happening.
I guess what I am trying to ask is, is there a certain forumla you could use that would be somewhat accurate in trying to do this?
I think the thing you’re getting at is, would the perfect physique scaled down 5% (or whatever) in every dimension still look right? Most of the measurements could be adjusted proportionately, I think. So if you’re five percent shorter, aim for a 5% smaller waist circumference. Your weight would be proportional to the cube of the difference - that is, our ‘scale model’ who’s 5% shorter should weigh 85.7% (.95[sup]3[/sup]) as much. Distances like the circumference of the arms and stuff (I assume these are the sorts of measurements bodybuilders use) would vary proportionately with height, so your scale model would have 5% smaller (in circumference) biceps, and so on. Seems to me he’d be able to lift 90.3% as much (.95[sup]2[/sup]) since I believe strength is proportional to the size of the muscle’s cross section; the cross sectional area would decrease by the square of the ratios, since areas are, like, quadratic whereas volume (and therefore mass) are cubic.
Anyway, outside of a small range, I don’t think it would look right. People who are taller are not shaped like scale models of shorter folks, nor are they simply like versions that are stretched vertically. The actual case is somewhere between those two extremes. To maintain a stable body mass index, your weight should remain proportional to the square of your height, while a scale model’s weight would be proportional to the cube of the height. (Let’s skip the discussion of how the body mass index is not always valid; it just gives a general idea of how weight varies according to height in most people.)
So someone who’s six feet tall is 20% taller than someone who’s five feet tall, but they’re not gonna be 20% bigger in every dimension. The scale model would be a close enough approximation to normal if you were talking small differences in height, but if you made a drastic change in height, I think the scale model would end up looking quite odd, because the fact is that short people and tall people simply naturally have differently-shaped bodies. I’m pretty sure that the perfect physique on someone six feet tall would just end up looking bizarre scaled down to five feet tall, because it wouldn’t be in proportion to the shape of real five foot tall human beings.
I hope I was clear enough here and that I haven’t made any gross errors of calculation. I’m a little drowsy; I might not be as articulate as I think I am. 
Who’s got the perfect physique, anyway?