There are two 701 engine models. There is a 701 engine with 61x cases and 61x cylinders which came originally with a single carb. There is also a 701 engine with 62T cases and a 61x cylinder which comes originally with dual carbs.
For the 62T engine there are conversion manifolds made by blowsion, Riva, and some others. There is also a UK based company named Air Time Products that makes a true 62T 701 conversion manifold.