Something like that would be good for 11.50 something around here at 2800 feet based on someone I know who has a later model Duster set up set up kinda similar.

Think 6000 - 6500 would be a good rpm limit. You'll have to run it with those gears and see what you get thru the lights. Too much rpm and a gear and/or tire size change may be required.

I know of people who have broke cast cranks, but they were in cars raced hard every weekend for several years in a row.