I've Built so many BBC's I stopped counting ... Mostly everything in street and race cars, and like others have said there is nothing wrong with them "mostly"
I recently finished a 632 Tall deck with best of everything parts for a 67 Camaro Pro street car - near 1000HP NA on c16 still cheaper build than my 1000HP Blown LS on e85
Since you are buying and not building, you have to live with the choices someone else made.
The general rule "There is no replacement for displacement" applies and they sound great
But in the general the rules and actions are:
Big Blocks can be built to make gobs of torque and good Horsepower at far less than an LS costs, but their are caveats
1. they are Really heavy even with Alum heads they weigh alot and the weight is even across the block so the CG is higher way higher
2. The parts are big and heavy and don't like to be swung around fast. If you keep the RPM down even a stock BBC will live forever, spin it fast and it will cost you
3. Canted valve heads are great for flow but cost ALOT TO MAKE LIVE AT RPM - the parts are just heavy and big springs wear guides like crazy (think smoke)
4. Its really hard to "cam" one for all RPM ranges - you will have a monster down low and run out of steam on top (5000 rpm) or you will have a good runner down low and a monster up top - but thet requires "baller dollars" to keep living I have turn them 9,200 RPM - but that cost cubic dollars
5. They run hot - the cooling design is really bad compared to modern engines, big heavy water filled radiator and 16" fans needed if you make any HP
6. Spend the money on the bottom end and Rect Port heads and you can add a little boost and easily get 1,000HP+ on Pump gas
7. Most people don't like the power band in a sand car - in an LS Turbos and Blowers build the TQ to get the mass moving and then HP out to keep it going, even NA's rev quick - Nothing is smoother than an LS IMO - built right and even from the factory they rev fast and smooth. . . BBC's rev slow - even drag cars need big convertors to get them past the slow rev zone - and you leave on the converter at 4500-5500 RPM and the Run to 7000 or 8000 shift happen fast with gobs of TQ but its a freight train - in the sand you want to get there quick and do it off idle. A GOOD BBC will want to flip the car over before it moves it straight down the sand.
If you ever raced a BBC on the street you know that a clapped out VW will beat it in the first 250 ft. because the BBC car is boiling the tires rather than moving - that kinda why I built them for the street.
If I was spending my $$ on a sand car and did not have an Albins or S4D and I wanted a "handler" and duner I would go LS - but different strokes .., etc.