The go to prop for the MVVS 77 is a 14 x 7, it is a torquer and will idle at 1,000 rpm when so equipped. I had an MVVS 61/LS, not officially called a long stroke but was one. I tried a 12 x 5 Grey Graupner, it shook a Bruce Tharpe Venture 60 like a rag doll. A 13 x 6 cured all of that.