In FAST, anything along those lines would be legal........ as long as it looked stock once installed on the motor with the carb in place.

I think it’s real easy to reach the point of extremely diminishing returns when it comes to modifying the stock iron intakes, especially when you factor in that both sides of the motor(intake and exhaust) are pretty heavily restricted.

You could use something like a Performer RPM as the (unattainable) benchmark to gauge how well you’re doing with your efforts in modifying the stock piece.

I’d say the three increments to baseline would be:
- an unmodified stock intake
- a DP4B with some mild port matching and mild divider work
- the ootb RPM

With all other aspects of the car “correct”, this would give you an idea of how much ET is on the table.

If the RPM was only worth say .15 in the 1/4 mile over the untouched stock piece........ how much time and effort do you wan to invest in it?

I would think the mildly tweaked DP4B would be the best indication of what you could expect out of the reworked stock piece.

Attached is a pic of the one on Harry’s Bee.
He did the bulk of the work himself........ I pretty much just smoothed over the rough edges and did the port matching, and I didn’t go all that far inside the runners either.

I will say if I had one to do from scratch, I’d do the plenum a little differently....... whether that would actually be an improvement or not is a different story.

Oh, and working on an iron manifold with a carbide in a drill, while kneeling....... in 90deg heat???
N-F’n-W!!