[Mr Pops]

So I was talking to the owner of a local transmission shop today and He was VERY disappointed to hear that I was planning to use a 700R4 my 68 Burb. (3/4 ton 4x4 with a mild smallblock) He said that it won't hold up. I realize that it's not as strong as a TH400, but I want to have the best of both worlds with low speed towing gears (4:10's) while still keeping my RPM's down on the highway with an overdrive tranny. My 76 Blazer has 4:10's and an overdrive and so does my 02 Suburban and I love this gear ratio/tranny combo. This tranny shop guy advised me to go with a TH400 and a higher speed rear end.
Any thoughts on the reliability/longevity of the 700R4? The 700R4 in my 2wd 76 Blazer has been awesome for the last 7 years, but I realize it's a much lighter vehicle and doesn't do any towing..