First off, I'd like to quote SuhaibKiani's advice to me, when I started a rebuild of my own.
"What do you want from this vehicle?"
Ultimately, that is going to dictate HOW you play around with it, WHAT you play around with, HOW MUCH to play around with, and what you EXPEND upon it.
Ask yourself these questions, time after time, and vector in the cost factor each time you do so.
Do I need a body-off-the-frame rebuild?
Is an engine swap warranted, or should I just overhaul?
What work is required for the suspension?
Is the frame good to go?
How badly do I need for ergonomics and aesthetics to be a part of the rebuild?
What sort of tyres do I want?
Where do I find the Ustaads that will be able to undertake this project, expertly?
What amount of money am I ready to pay, at the end of the day?
These basic questions, will allow you to prioritise, and help in channeling your efforts to the right point(s) of focus.
Don't rush into it. While most of the people reading this thread are well-wishers by default, YOU are the one who's forking out the money, inevitably.
Suno sab ki...karo apni.
Take time out to research what you'd like to do. Pick up ideas, and add them to this thread. Pictures. Experiments. Wacky, crazy thoughts. Make this thread your online Journal / Scrapbook for your thoughts. Follow these crazy ideas, with a continuous, painstaking research into the economics involved.
When you've answered all of those questions, repeatedly, and the vehicle has firmly taken shape in your mind...you'll be ready. Then, and only then...take that plunge!
I'll be following this thread closely! Best of luck.