Gen3 Engine Swap- Or not?

[Calitruckgrl1]

The 327 fuelie motor in my '65 GMC has seen it's day, and it's obvious that it is tired out when driving my truck around. I'm not sure exactly when it was put in the truck as I've only had my GMC for about 6 months now.

I got the truck not only because of my love for vintage autos (it was love at first sight), but also to tow my 1972 2-horse trailer that I'm currently restoring to match the truck.

In considering an engine swap, there are so many options it's overwhelming. I just want a reliable tow vehicle. My brother has suggested a 6.0L gen3 engine; other friends have suggested an older 350 or 454 would do just fine. Gas mileage is a concern, but i hope to improve that a little bit anyway when we swap in an overdrive (3sp auto right now).

Any opinions, experiences, or general help regarding my dilemma would be greatly appreciated! Thanks, Sara