I recall in one post on the PY site that the only improvement with the 4/7 cam in terms of HP was in the upper RPMs. No gain in lower RPMs. I had the choice to doing that with my roller cam and decided not to in the end.

The smallest roller cam that I have seen recommended on the PY site was a 220/224 grind that one guy was using in his 400. He liked it a lot. He said it made the motor feel bigger.

I have the same motor goal, a cruiser with the torq down low. I have both a 350 and a 400 to chose from. I was reading a ton in the PY archives I could find no evidence that anyone was getting better millage with the 350 over the 400. This build is for my 326 tempest with 2:56. I just love cruising with it but it has nothing for torq and it currently gets around 20mpg on the highway. It just smooth and comfortable down the road.

PY's GeeTeeOhGuy has a 400 with small valve #15 heads and a 068 cam that he consistently gets around 21mpg and enough torq to spin his posi 2:56 rear. So I'm planning an a very similar build. I have the #15 head already. The small valves gives plenty of intake velocity and about 9.3:1 compression on a 400. The 068 has a wide LSA that make it idle smooth and gives a wide flatter torq curve and plenty of vacuum.

Another archive post a guy had compared several cams and posted .10 better in the 1/4 with the 068 with 1.6 rockers over the summit 2801. He also said the Lunati super cam was his all time favorite cam. It has shorter duration number like the 067 but higher lift like the 2801 and a tighter LSA. He said it was like an electric motor off the line and could spin his 2:56 gears with ease and claimed MPG around 22 with that combo. I have been really considering it but the 068 is tried and true. Remember the lower the duration the lower the peak torq will be in the RPM.

The cam you mentioned in the first post sounds like it would work. I'm sure other might be able to comment more if you provided more detail on it.

Having considered the roller cam my self I just cant justify it. The roller shines when you want high lift and shorter duration numbers beyond that they are just an expensive PITA. Have yet to see good Pontiac hydraulic roller lifters. The flip side is HFT cams going flat. But sounds like if you go with Johnson lifters and use the right additive and break in lube you shouldn't have any issues.

So I don't know what the priority is for you but just some food for thought.