You might try Perceptol stock. The time for EI 200 is 11 mins. You've managed 4 stops less than 200 so you might try, say 30% less than 11 mins

I'd cut off the first few negs and develop them as above and then go from there.

Just curiosity on my part but how did you manage to dial in 5 stops less than the box speed?

pentaxuser