Holley Carb Help

[Hewfil1]

Okay, long time since my last post but I'm finally digging back into my truck and I encountered an issue. Went to rebuild the Carter that was on it and it's trashed. Rebuild kit went fine until disassembly and I realized many of the internals were corroded and couldn't be removed. So I went to the garage bench and dug around for a new carb. I found myself an old Holley 1850. Now, I have a few questions.

1.) I'm seeing two types listed for the 1850. 0-1850S and 0-1850SA. Mine's an older one and I'm not sure which one of these it is.

2.) If I just buy the 1850 rebuild kit will it work with either one of these models?

3.) It is not an electric choke and the Carter that was on the engine had an electric choke. Can I get a conversion kit for the Holley to make it elec. choke?

4.) I can't for the life of me seem to get a straight answer from the internet of what bore type it is. I know I'll need an adapter but looking through them I'm so confused and don't want to order the wrong one. (If it helps my current carb is a Carter AFB 625CFM)

Sorry for the totally clueless post. I know a lot about small engines and their carbs, but I'm really new to vehicle carbs.