Realistically, you'd end up spending the same amount of money on either engine, but you'd come out with less power and less potential for making more power. I mean, for 5 grand you can have a 450+hp 383 stroker out of a 350. Can't do that with a 305. And a 700r4 wouldn't be my first choice for a transmission either. Monte SS g bodies came with one of the desirable models of the 200r4, along with the GN, and 442. It's really the valve body and some internal components that make them better out of the box than say one from a
caprice or
delta 88. the GN has a higher stall converter (something like 22-2600 if I remember right) because it was behind a turbo v6. With the 700r4, you'd need a new cross member, as I'm sure has been mentioned in here quite a few messages ago. A 200r4 would drop right in, and have better gear ratios for a car. Still a 4 speed auto with overdrive (4th). but weighs a bit less and saps a bit less power.