I am converting from a 153 tooth flywheel to a 168 tooth so I can upgrade to an 11" clutch. Can I and where would I find a replacement snout for the conversion or would I need to buy a whole new starter? Thanks for your input....

Find a local shop that rebuilds starters. They should have what you need. Or you could buy a replacement starter of the type you want and return a core of the type you do not want.

Ditto on the local shop, the local one here has gotten my business for years. Recently replaced my kids bendix drive. Counter guy at Schucks told her she needed a new starter. Bendix was $12 and change, 20 minutes to replace and popped the starter back in, good to go.

Junkyards would be a good place two.

The best are the truck snouts, cast iron rather than alluminum!!

On bendix drives and solenoids, go to your dealer and get a real Delco. It will cost a little more, but will last a LOT longer.

GM direct drive starters are easily rebuildable, and fairly universal, with only a few variations over the years.

I presume you also know that if you change from a 153 tooth flywheel to a 168 tooth, you will also have to change bell housings.
Also, you have no choice between alum or iron nose for the starter. YOU MUST USE A CAST IRON NOSE, the alum nose will not fit into the starter bulge of the bell housing. The alum nose for a 168 tooth flywheel will only fit an auto tranny starter bulge.