Hydramatic Trans - Replace or Rebuild

[Surfdaddy]

I went to the local trans shop to see if I could get the rear seal for the Hydramatic trans replaced and have it looked at and serviced. It's been sitting since around 90 or so and the trans seems to shift very quickly , like from 1st to 4th in about 100 feet. He said that depending on the condition of the internal seals it may have to be rebuilt and he may not be able to get parts for it. I asked about a 700R4 and he said I could get one for around the same price as the rebuild of the Hydromatic. I would like to keep the truck as OEM as possible but the idea of an overdrive and being able to go LA freeway speeds appeals to me. So, taking into consideration the cost of getting the adapter parts for my V6 would it be worth it to change over to a 700R4? The truck has 4:10's in the rear now and I'm sure I'll have to go through that in the near future so a gear change may be an option.