So it all started when I scored a built 305 Chevy motor for a bottle of Capt Morgan. Searching for a platform led me to an 86 720 with out the motor and trans but everything else looks good, front differential looks brand new considering it was laying in the mud and had a bit of water in the oil from sitting years in the rain. Question is I'm thinking a TH350 to put between the motor and transfer case, is there an adapter that puts these together relatively easily? This is going to be used for mud drags and maybe sand, the radiator is going to be mounted in the bed so I'll have some wiggle room. A 2wd trans will probably be the easiest to find cheaply but anyone have any experience doing this kind of swap?

Being that the transfer case is divorced to start with it seems that you would just need a custom driveline.
The front diff for a 720 is not an axle, the 720 4X4s had a solid mounted diff with half axles coming out of it going to the floating torsion bar controlled drums, which necessitated a custom oil pan on the stock engine.
It sorta sounds like you have a complete straight axle that is mounted on leaf springs, and you have a 720 that started out as a 2wd.
What state you live in?

No it is all stock underneath, 4x4 ifs and all... It came with a 2 inch body lift which is where I plan on running the coolant tubes back to the radiator. This might be enough (with spacers on the motor mounts) to clear the oil pan, if not I'll look around and see what Chevy did with their ifs/oil pans... When I found it the front differential was out of the truck laying in the mud, it's in the bed now draining the last of the water oil mix... The part I'm going to need would bolt up to the input side of the t-case and hook to the trans. A TH350 is preferred but most of these transmissions have a slip yoke... And I'm in Oregon.