I know nothing of the 545, but I have a A500 behind a small block which is what the 5.7 is essentially. Now there is one other choice, and that is the shorty 727 Gear Venders set-up from SMRE, but most do not like the price.

So if you looking to decide on the other three, the A500 is a really good choice when built properly. Mine has been flawless with SMRE parts in it and I can hit OD while at full throttle. I have 4.56 gears, and they are very streetable with it and mine has the low gear set to boot. The bad is it looses a little horse power because the OD is always providing a little drag unlike a GV unit. Love how it works, and should just about fit in your Cuda with just a modded cross member and it should bolt right up to the 5.7...

Now if I were to do it for my Cuda, I would go with the SMRE 727 shorty deal. I know it fits, I know my 727 will handle +700hp, and I know it won't drop the rwhp....I have an Ultra bell and can swap small block to big block without even pulling the trans...Did it last year, and they are easier to build.