what do i need to install a 3 piece crank in my bike. the bike is an 88 schwinn and the crank is an 86 takagi. the bike has regular bottom bracket cups in it now. i work on bikes all the time just never installed a 3 piece crank. thanks for your help

There are a few different ways to do this.
simplest is to purchase a "conversion kit"
The essense of the conversion kit is a spindle and
bearing races. you can use the one pc crank bearing and cups so there is no real need to remove the old cups.
Or, you can purchase a sealed bullseye (or similar)bottom bracket.

is this a common kit? any bike shop would have this? then where can i get this kit? thanks