I have a Crane roller close to that. You will need an 8" 5300 to 5500 stall to work best. That is not a cam you want to run with nitrous and not a good one for the street. You can run anything on the street, it's just not a wise choice. 112 to 114 lobe centers make a cam that big a bit smoother...

575 to 625 with those heads

I would be concerned if you have two breathers and still have enough crankcase pressure to make seals leak. Sounds like the rings are not sealing well. A vacuum pump will only mask the problem.

I believe there is a Rockett distributor in Ocala. I think their website had the info.

What trans/converter and gear ratio? Need to know this before you order a cam. Don't waste you time with a dual plane unless street performance is your goal. You will always run faster with a single plane on a 406 with the AFR heads. A Vjr. is a good choice with a 2" spacer, a Super Victor is t...

Look toward the Dart block over the World. Block material and machine quality seem a little better.

I would expect a race engine to go faster with a tunnel ram vs a single carb manifold. More airflow potential whether you run carbs or a hat.

You will run out of head flow after about 6800 to 7200 unless they have serious work done to them. They may rev higher, but won't make power. I would keep that block under 7500.