I am planning on building a supercharged 302 stroker for my 63 unibody and I wanted to know how supercharging affects compression ratio, I know it raises it but I was wondering by how much, and what would be a safe ratio to have for a street motor on 93 octane.

 

Supercharging doesn't affect CR. It increases cylinder pressure, and if your CR is too high to start with, you can't run much boost.

What is your power target and budget? Those will dictate your direction.

Google "302 ford supercharger" and find:

174 Series supercharger kit for 289-302 Ford polished

amongst others by the dozen, including how-to books, magazine articles and stuff for sale.

Do you want roots, like above, or centrifugal?

Vortech (4FL218-140SQ) Supercharger System - Satin Finish

Do some research, this is an expensive path to more power. To run 93 gas, you will have to limit boost, or go low compression blower pistons.

400+ hp naturally aspirated 331s and 347s can be had for far less....

 

Buy and read "Maximum Boost" by Corky Bell. It is the best book I've read on the subject of turbo and supercharging and is written so even I can understand it.