Technical SBC Starter Question

Hey boys I am Phone- Helping an older gentleman with his '57 Chevy car w/ a 283. He is removing the 3 spd std & replacing with an Iron PG. He got all the parts from someone who is now deceased & has found out he wound up with a 6 cyl adapter. I had a v8 adapter but gave it away so I know I don't have one. So then he went & bought an Aluminum PG & is having it rebuilt & want to use it. I don't know yet if he realizes that he is gonna have to support that trans some other way now or not. I have for him the correct flexplate & starter nose. He says his engine is a '58 model so my question is about the block accepting a late starter. Are '58 blocks drilled for vertical mount starters? I know they didn't use vertical mount starters then. I don't think he knows just what to look for under there yet. What year did Chevy start drilling those blocks anyway?
Thanks

 

57 was the first year because of the Turboglide.

 

Here’s what a 57 283 Turboglide starter looks like.

 

58 block should work with the starter that matches the 168 tooth flexplate.

and just recently someone needed an iron PG for a 235....

 

OK great, I got this covered!
Thanks a Lot!