i have a bigblock 440 non stroker and friends have smallblocks with 4.0 cranks and all out indy heads on the small ones.all cars are A bodys but add the weight to et numbers and do the math.
my build is a 440 with old indy heads 270cc runners @ around 335cfm. stock crank carrillo k rods je pistons 2.19/1.88 262/265 around .640 lift 3170 with me in it.3rd pass ever on new engine 10.20 @131 with the converter way too loose at 5800.
the 4" crank small block guys cars are wicked fast small blocks. everything in the engine is good stuff. only the block is stock.
they work real well but are already built with full roller and the biggest valves indy will let installed with out rubbing.(the guide location sucks. some are .015 different or more between the valves.
there are many pros and cons to the great bigblock small block topic.

i have a non high strung 440. they have extreemly well running 4" small blocks with fully ported heads and full roller cams. i can get around 370 to 380cfm fully ported. i am going to lean twards being a 440 or 400 block with a 3.9" crank for the E body.
just remember go small block r3 or higher the weight thing may get closer to a bigblock.
either way it will haul ass cause it is not a ford or gm product. just have to look at where you end up with either combo. money wise if it is the same either way the bigblock combo will have more to throw at it eaiser. but it is impressive when a duster runs real low 10s on a stock block 4" small block A body and not having to hit 8000 rpms.
have fun what ever way you go. i love my 440. just get someone who cares to do the machineing. my block was done on a cnc engine mill.
the other guy was fired LOLOLOL.