Amal valve is still a great boost control and if you use the correct size jets inside the pipe outlets you will have a great boost curve. Put your money to better use imo as an amal valve second hand and working is only 20 quids worth. You got loads to do before you thin about boost control issues. Have a read of some technical essays that are on a site which explains how to set them up correctly and make the most out of them.

A bleed valve should never be used!