Well this should be an easy swap. Like you said you need a fuel pressure regulator so find an adjustable unit. As you state the TBI fuel pressure is not too far off from what the carb will need but find the specs and suggested fuel pressure for the carb you use and set the regulator at that spec. Another bit of good news for you is that the 700R4 is not a computer controlled trans, the trans just needs a TV cable and linkage at the carb. Lookup the specifics and kits online, this geometry MUST be correct or you will fry the trans in a few weeks. If you can not figure it out get a trans shop to do it for you.
The computer only tells the transmission when to lock-up the torque converter. I ran a 700R4 for a year without any lockup since something was not working in the computer. I gained 2 mpg with the lockup hooked up!!!!!! I bypassed the computer with a few simple wires so it now has a switch on the dash to turn the lockup on and off, as well as a vacuum switch to make sure the lockup turns off when accelerating, and finally a brake switch to turn off the system when the brakes are applied. When I first wired this up i simply hot wired it to make sure the lockup was working and then I began adding switches so it would only lock up when I wanted it to. be sure to run the brake shut off switch because if you do not then you hit the brakes hard the engine will stall and you could be in a HUGE accident due to no power steering and power breaks ect.