how to change from a 350th to a 700R? help!

[Brently]

i am in need of someone to spell out how to change over a 350 turbo to 700R - i have a 700R out of a 86 Astro van - can someone tell me if this will work - is the length the same? is the spline of the yoke the same? what do i need to do to lock up overdrive? what all equipment will i need to do so? i am putting this in my 71 swb chevy truck - it has a 350 motor in it with a 3:42 posi unit behind it - trying to get better highway gearing and better gas mileage - any help would be appreciated - thanks, Brent