Whats wrong with the 350? Honestly, unless you were pulling a 15k fiver I would just purchase a Goodwrench 350 if you need a new motor, add some headers, maybe swap out the Cam, possibly the carb and You should be able to get pretty decent power numbers and great reliability.
If you are pulling a bigger load and have high rear axle gear ratio I would look into replacing the rear axle with a lower gear ratio before diving into a full on engine transplant.
I love that body style dually.. btw..
Thanks!
Jeremiah
