towing with a 4wd?

[Flatty]

I want to get a 67-72 Chevy or GMC pickup truck to build into a tow rig... I plan on towing a flatbed car trailer with a built FJ40 rockcrawler on it. Here is my dilemma...

I started this plan with the intention of swapping in a cummins diesel motor, but the total cost would have been VERY high, so I put a stop on that one.

My other option is this: Vortech 6.0L with a 4L80E behind it running to a 205? and then off to a dana 60 in the rear and a 44 up front. I will rebuild all the suspension, and throw some 4" lift springs on there (probably custom made for its purposes). I plan on running a set of 35's on 17" wheels.

Here is my question to you. Do you think this would be able to tow a flatbed with no problems? Does anyone here tow with one of these types of trucks? What issues do you run across?

Thanks
Dima