I can tell you, that you are not too old for this.
I have a slow metabolism always did. I was very involved in Gymnastics at a younger age so know all about this. I have seen ripped 50+ year old ex-gymnasts.
First question to ask you is why very big? Would you not prefer to have explosive and real strength like a Gymnast? Gymnasts have the best bodies with real strength without looking like gorillas.
If you are not overweight, you can get ripped in 2 months with very intense, strenuous weight training, but this is a very bad way to go about it for various reasons 1) It will age you tremendously, I put 3 years on my face doing this. 2) It makes you injury prone 3) If you need to burn fat weight training is not the best way. 4) Your recovery is slower due to age.
I would set out 6-8 months for your objective, you do 30-45 minutes of intensity training 4-5 a week, and step it up monthly. It should be intense but not strenuous.
I bought a gymnastics home fitness dvd set (called gymabstics) it is very corny the production is crap, but the routines are good. I know its a bit homo, but it saves me time and having to go to the gym and I hate having to motivate myself. The first 3 months have very little upper body work but are great for the rest of your body so you can get a book like Never Gymless or get Gold medal bodies Floor series and supplement or alternate 2 or 3 times a week, plyometric strength will be your objective for Never Gymless.
This is the way forward you will never be in such shape in your life without the costs and motivational requirement of a gym. I've done gorilla bulking up and massive weights and won't go back there again.
