Being that yours is stage 6 on an RB, you've got the extra-wide (stage 6 rb only) intake.
I don't have my chart handy and didn't check to see if the number you gave was a casting number or a part number/box number......but FWIW the 337 intake is standard RB width.
As far as I know Mopar never marketed it as such, but it should have been OK (or pretty darn close) for a B block with stage 6 MW heads....but the double valley tray probably would have entered the picture in that configuration, so that's probably why Mopar never tried to sell it for that setup.
I am pretty sure at the time it was released, repro iron MW heads had hit/were about to hit the market, and (understandably) it was mainly marketed as a single 4bbl for that configuration on an RB block. Should be bolt-on for that configuration with no valley tray issues etc.
The 337 is no-go go for RB with stage 6 unless a guy wanted to run the spacers AND a double valley tray....which could be interesting....double the chances for both oil and vacuum leaks...not exactly an ideal setup