[chevroletracer350]

Man, that is a great looking truck.

Well, being me, I'd keep it all original. Even with the original motor in it. That's what I like, but not everyone is the same as me. Also, you have a second motor sitting there..
You could always drive it until it blows, then put the 327 in it.

All original is worth more most of the time I think, not to mention, neat as heck.
But if it's going to be your truck until the day you die, then do what you'd like with it.

I guess down to it - If it's getting bad and it's your DD, I'd put the 327 in it and work on fixing up the 307. I'd keep the stock stuff around, that way you can always put it back if you want to, or sell it.