According to the Mopar chassis book 8th edition; the center of the starter nose support in the bellhousing is 7.08" measured from the center of big block bellhousing.
I assume this measurment from the book is for an 11" flywheel. The small block bell measurement is less, but does not give the measurement. It appears to be about .25" less. The book does not specify which BB bellhousing in pictured in chapter 4.
The slant 6 distance shows to be 6.219"
I measure approximately 4" from the starter nose center to the outer side of the starter motor. Motor diameter about 2.8 inches.

Reclocking the starter motor in relation to the crank would bring the motor closer to the crank.