B vs RB

So this kind of goes along with my other thread: Big block conversions, do it again? Now I am settled on going big block for the barracuda. I checked the BB 727 that I have and it has the bosses for the floor shift auto, so we are good there. I already have a 1978 440 short block in the garage, it will need to be completely rebuilt. But I has the bosses on the driverside of the block for the A-body mount. I found a complete 383 for $300 not to far away from me. So what would you do B or RB.

I should say manual steering and brakes isn't that big of a deal for me.

Is there a lot of difference in how much more space the RB takes up? If not I'll use what I got and build a 440 Barracuda.