Flaws are as follows:

The oil pump housing is made of aluminum. This leads to early wear. And when the housing has grooves worn in, common enough, the oil pressure at start-up will appear normal. Then once the motor warms up, the larger gaps, due to expansion, will allow oil pressure to drop into dangerous zones at lower rpms. This is dangerous if you are putting a load on the motor at low rpm, then quickly revving to high rpm. the oil pressure cannot keep up with the fast acceleration and will run the 7-8 bearings almost dry.
This can be worked around by using either or both a Milodon pickup, and/or a bypass line under the intake manifold (explained later in detail).

Lack of a large choice of intake manifolds. The only choices for intakes are the Edelbrock Performer and Torker, the Offenhauser 360 and dual quad. Other manifolds used to be on the market, but have been discontinued.
For most uses the Edelbrock Performer is the best choice. It will allow a wide power band, and gives good response time in most rpm ranges.
The Offenhauser 360 is a better choice for a slightly more modified motor. I prefer this manifold as is, and with modifications. But it will not give the same extreme low rpm performance as the Performer.