Rob that 28 of mine with small blocks was very well balanced ... honestly with todays technology I have no idea why anyone would power a 28 with twin BBC it makes no sense whatsoever.
As for my 24 Pantera well that was a SBF 351W

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originally back in 85' it was sold as hull and deck and the owner powered it. Not very fast but RELIABLE to the nth degree. Only replaced the aluminum Edelbrock exhaust because it was like 20 years old and the points condensor once...other than that just oil and plugs.
I'm going SBC on this one and see if it will provide the power I'm looking for with reliability and not spending a lot of $$$$ like I know a BBC would be.
Here are pics of the 351W from my first Pantera 24(left) and then the 350's from my 28' (right)