No, a 700r will not fit a 350. The 700r is an overdrive transmission designed to increase fuel efficiency in vehicles with larger engines and it is incompatible with the smaller 350 engine. Additionally, the 700R4 has different gear ratios than those found in the 350 and therefore would require additional modifications for compatibility. Furthermore, due to its size and weight, installing a 700R4 on a small block Chevy like the 350 can be difficult or impossible without serious modification of both parts as well as their placement within the car's frame. Ultimately, if you are looking to upgrade your vehicle with an overdrive transmission then you should look into other compatible options such as the 200-4R or 4L60E that were specifically designed for use on vehicles with smaller engines like the 350.