I can't offer specific information, but Lycoming talks about the "Same Engine" myth in one of their reprints. They point several major differences, such as conical mounts, in HIO-360-D1A vs IO-360 engines (yes, I know you said B1A). Check out pg 28 of the General doc listed on
this page.
Any negatives to watch out for trying to use a Lycoming HIO-360-B1A engine in a vans? Injection intake configuration, crank shaft, etc?