Which 700r4 for my 88 silverado

My 1988 silverado has a 350 THM in it presently, which is only a three speed. Which 700r4OD trans from other years and different vehicles will work with this truck. I am also concerned which toruqe converters should be used. The truck does have the digital speedometer as well. At present it has a 305TBI, but, i may change to a 4.3TBI. Thanks