If I'm running 3.42 gear in a 10 bolt with 295-35-18 tires and if I go with a 700r4 tranny my motor is a 350 olds with a 520/523 lift my question will a 700 r4 be a choice to go with?

 

If your original trans was a TH350, then a 200/4R will be a more direct bolt-in.
Move the crossmember back, same driveshaft, add a TV cable.

 

The tire size you mention is 26.13 inches in diameter. Using my gear range calculator, it says you'll be at 2156 rpm @ 70 mph. Gearing shift points may be a bit low rpm-wise, but a shift governor calibration kit will solve that. 200R4's get most of the love around here, and if my car had not come with a 700R4, I would have likely gone that way too. Since I have a 700, I figured out how to get it to run the way I want and am very happy with the results. It has a shift improver kit, re-calibrated governor, 2200 stall, hydraulic lock-up conversion and assorted internal upgrades for longer life and power handling.

Tim