273 Supercharged...ITS HAPPENING PEOPLE!!
Sounds like a fun build, I look forward to progress updates.
Just one question. the FAST EFI you're going to use. is it a EZ series or XFI series?
From memory FAST don't recommend using the EZ series for forced induction, they may even deem it "not suitable". You may want to check on this.
A lot of "plug and play" self tuning EFI systems are only tuneable through a method known as Alpha-N which means it uses the throttle position and RPM inputs to determine engine load and in-turn the user can define the fuel/ignition settings. Some are even fuel only!
More advanced (and pricey!) kits like the FAST XFI systems are able to additionally use the intake's MAP sensor and/or an airflow meter/s parameters to accurately tune the correct fuel/ignition tables for forced induction.