I've shot a fair amount of Classic 400, in 120 and 4x5. I give it box speed, and process in either HC-110 Dilution F or Parodinal 1:50 (same as F-09 1:40), either way for just about twice the time I'd give Tri-X in the same soup. The above advice of 10-20% increase is completely wrong, both based on published times and on my experience with dozens of rolls of both Tri-X and Classic 400 over the past couple years.
A "look similar to Super XX" would be a grainy, gritty image with a very linear tonal range, but in fact, IMO, Classic 400 (even in a Rodinal-like developer) isn't as gritty as Super XX was (though I've never used Super XX, I've seen scans from it); it's closer to 1970s vintage Tri-X, and about the same speed, rather than the slower, grainier Super XX of the 1950s, at least (Super XX, like most other films, did change a couple times before it was dropped in the early 1980s).
FWIW, Classic 400 is probably the best-value ISO 400 film on the current market -- I'm currently trying some Foma 400, but so far don't like it as well; I'll probably go back to Classic/Forte/.EDU (Made in Hungary) and standardize on that across my formats (especially now that I can get it in 9x12 cm).