Ken,
If you are going to intercool your intake, have you considered a roots blower? Eaton M-62's and M-90's work well with 3.5-4.5 l engines and can handle up to 10psi. They are cheap and plentiful, as they were used on the Buick 3800 (231) Grand National and Phorde 3.8 supercharged V6's (T-bird). They make plenty of boost at low RPM because they are positive displacement. It is pretty easy to make an air-to liquid intercooler yourself, or you can use a volvo air-to air intercooler. I am considering either this or a big turbo for eventual use on a 235 or 261. I am going to plumb in an oxygen sensor in each exhaust manifold for monitoring the mixture. I have a design for a cheap a/f mixture meter based on a 1 wire O2 sensor and a cheap LED bargraph driver chip.
