TBI or 700R?

[herb101]

Which single mod (TBI conversion or 700R4 swap) would give the best mileage improvement?

For the requisite background, the truck is a 71 K5 with 350, Edlebrook carb, TH350 and 3.73 gears, running 35's. I get about 8-9 mpg now and the 30% gas price hike has me thinking...

I have the ability to perform either swap, so install costs won't be a factor. I'd like to do both eventually, but which should be first?

Thanks,
Herb