I suggest the genuine Denso unit that Mancini carries. I'm running a factory 318 Dakota starter on my 143 tooth flywheel with Doug's headers and it fits fine.
Gus
That's what I used on my 65. (It's an automatic.) I didn't know if it would work on a car that had a direct drive starter originally.
I'm pretty sure only the early production 426 HEMI used the direct drive starter with a special bellhousing that wont use the late model gear reduction starter.
Double check your bell and flywheel before you bolt it all together
Gus