It is a matter of personal desire. I put a big-block in my old truck just because it was different. I had always built small-blocks (since the '60s) and just wanted to do a big-block.
It does cost more but, on the other hand, it doesn't take nearly as much modification to make good power. I'm not talking about winning races here, but about good, strong, tractable power for a truck that is driven on a regular basis. The kind that sets you back in the seat at low RPM.
My biggest problem with the conversion has been cooling. Big blocks make a lot of heat, and will need a good cooling system. You should have no problem with your truck- you've got lots of room for a big radiator and aux fans if you need it.
