convert 96 454 mag to carb with roots blower
 

I want to pull the fuel injection off my 454 mag and replace it with a roots blower and a carb. What else would I have to change to make this conversion work.

You didn't say what your objective is: do you want the power or just the look?
If you want the look, just address the fuel pump and install the blower with a different ignition.
I don't care about the looks. For power, you need to do something about the fuel supply-pm me and i will discuss this as there are many possibilities. You will have to change the ignition. I recommend MSD for availability and past experience.
The camshaft needs to be changed. Yours will work OK but you will miss a lot of blower advavtages. The best blower around is the Whipple 3.3. If this is too much, Littlefields are about the best I have used for a Roots style. Whatever blower you go with, BOOST REFERENCE THE POWER VALVE(S)!!!!!!
There are too many combinations to discuss here-my fingers are tired. For more info, pm and I'll try to help. I have done this before!!!:D

My avitar to the left are 1994 454 Mags that had multiport fuel injection. I needed to rebuild so I did this. It can get quite costly. You will need if you do not already have:

Roller cam
Roller rockers
New exhaust
New ignition
Weiand 256 blower
2 Holly 700 carbs
Flame arrestors
Hydraulic steering (be safe!!!)
Electric fuel pump (depending on Gen V or not)
Valve covers (depending on lift)
Misc fuel lines
Oil temp gage set
Dyno
On and on for the little things....

The little stuff really adds up. I have about 40k wrapped up in the upgrades and I did all the fitting and engine pulling as well as put on the steering my self

I think you would be better served by a change in cam, new exhaust, and MPI reprogram. Cost would be about $2,000 plus labor. Here is someone that may help:

http://www.azspeed-marine.com/

Contact me if you really want to go the blower route.