I'm building one now for mine.Those F-Head 161 engines are hard to come by. A larger displacement than 161 6 would be to long for standard jeepster engine bays but the 161's will more or less just bolt in with minor motor mount changes. I just recieved a 161 F-head myself that I will be putting in my 49 Jeepster.
The F161 Hurricane was used in the 1952-1953 2wd Willys Station Wagon (Model 685) as well as in the Aero.Being a truck guy I don't often check this site. I never knew they made an F head 6 banger. What all vehicles used them?