Get yourself a GOOD rebuilt OEM {Delco} starter correct for the application and forget about all the rest of the universals and trying to make them fit.. You want a good starter that easily cranks 600+ HP? Then get one of mine. ..

 

I just did this conversion 2 weeks ago. I got a starter for a manual tranny vette of the same year and it fit perfect. We did have to bend the inspection cover a little to stop the flywheel from rubbing it (the inspection cover), but you won't really know that until you start it up.

 

That's exactly the tidbit of information I was missing.

I didn't understand what the four holes on the starter block were for and I was trying to use the two holes that are there for the 153 tooth flywheels instead of the 168. There were basically no instructions with this starter other than unbolt old, bolt up new. When I put the starter in position and looked a little closer I could see that the two holes I was trying to use would have put the starter in a position where it would have just hit the flywheel and not been able to fully extend out of the starter motor. So now, using the correct holes, the starter sticks out a little past the edge of the block but it lines up much better and covers the entire starter hole in the dust cover.

Now my only problems are fairly minor. There is a "bead" for lack of a better word in the dust cover that is keeping the starter from sitting flush with the cover. There's only a small portion of it in the way so I'm assuming I can "modify" the dust cover with my special tool (hammer) and flatten it out in that spot to make the starter fit flush. You can see what I mean in the pictures below.

Then my only other, extremely minor, problem is that I won't be able to get the screw back in the dust cover under the starter but that shouldn't be a problem and only I'll know it is missing I guess.

Now, if I've still got something totally screwed up in the pics below, please be kind. I haven't seen the starter on this engine in 10 years.

 

Shinoda Vette
The main difference in the Chevy starters are the size of the nose and the bolt pattern. (besides the obvious differences in general size) The early starters used a large cast iron nose which was later changed to aluminum. The later style used a much smaller nose such as the one used with the 621 bell housing. A starter with both mounting holes parallel with the flywheel is for a 153 tooth ring gear, and a starter with a staggered bolt pattern is for a 168 tooth flywheel. Chevy blocks as far back as 1955 were drilled for both of these starters even though the starter was mounted on the bell housing. Chevrolet used the block bolted starter in their V8 industrial and marine engines before they were introduced in their cars. The pictures of the starters you posted are generally referred to as mini starters and they will work with both 153 and 168 tooth flywheels. These starters can cause some fit problems in a stock application but generally work well if you don't mind making a few minor mods. I like the Powermaster starters here.
153 tooth.
http://store.summitracing.com/partde...5&autoview=sku
168 tooth. http://store.summitracing.com/partde...5&autoview=sku

If you are using a 153 tooth flywheel with a 621 repro bell housing you will have to use a mini starter as the ones you posted. The shape of the hole in the bell housing won't allow the powermaster starter to fit properly when using the smaller 153 tooth flywheel.
Hope this helps.