I can’t help you with the Ford racing starter, but I can give you another option to consider.

Powermaster (www.powermastermotorsports.com) was extremely helpful when I was looking for a small gear-reduction starter to use on my V6 Alpine conversion.

They offer three different starters for the 289 engine with a manual transmission. Click on “racing” and then on 160 / 180 / 200 Ft. Lb. Starters. It looks like you probably need a 3/8″ offset version, but I am sure they can advise you on that.