You get that ruck home yet? Lets see the pics!!
An original motor would definatly be the easier to install, but a decent running 216 or 235 might be hard to find locally.. whereas 350's are a dime a dozen, and can often be found cheap in wrecked cars.
The whole 350 install sounds like a whole lot of chopping and riggin' to do.. maybe i'm not really a purist.. maybe i'm just lazy!
If I absolutely had to put a bigger, newer engine in one of my trucks, i'll have to say that 6.2 Diesel idea sounds pretty cool!