You could install the methanol injection nozzle right @ the 3 bolt flange adaptor.
The methanol injection pumps run about 200-250 psi, so it's going to spray into your intake manifold regardless if you are boosting 30 psi or just 6 psi.
http://mysite.verizon.net/res11pgkr/vehicles/buick8485.htmlMBHD
So how would one go about injecting water/alcohol with this setup? through the top of the carb or through the intake? I've heard of people making their own injection which sounds like a fun project. Im really excited to get this thing going!