A performer manifold would help, but I would go with a Holley 650 vac secondary carb (not the one with one fuel inlet) unless you're thinking about making it a performance machine down the road...if thatÂ’s the case, I would make it a Holley 650 dp.
I think the LD4B was an ancient predecessor to the performer. I've read lots of good things about it and it's sized correctly for the 318. The Holley 80454 is a 600 cfm vac. secondary/electric choke carb.
My plans for down the road a way different - I have a 340 block that will get a a 4" crank, so it's like apples to oranges. This is 'just for now' to have a littler bit more fun and not be so wimpy when they flash my time up on the score board!