sorry for not getting back quicker, been busy.
the hydroboost set up can be a good option for use instead of the vacuum style because it gives very good boost no matter the rpm or engine load. it is run off the power steering pump circuit. with the smaller space on the frame area for a vacuum booster it is a must to have a dual diaphragm unit in order to get the square inches of area to achieve good brake boost. the hydroboost unit is quite small in comparison but may require some fabrication work. see the link below for a few threads and pics etc.
http://67-72chevytrucks.com/vboard/s...d.php?t=202888