Go to your local parts place and get you one for a 79 international Scout with a 345. Or try to find you a holley 500, part number 4412, IIRC. A great site for IH motor stuff is
95 IH 72 passenger transit school bus w/ DT466 and 545 Allison.
79 IH Scout II/392 (0.030 over) Hamilton Injected/727/D300/Full size axles/36" Swampers/Lockers/OBA/38 gal Custom fuel tank, roll bar, tube doors.