I had a similar problem with my 450 ( not a quickfuel & mech. secondary's ) I had to much timing in it. ended up pulling some out to be able to set the idle.
mine I was never able to get it to where I was happy with it. the mechanical secondary's were just to much for the slant. after thinking about it now, I could have just eliminated the seconday linkage and wired them shut and tuned it like that.
my build is similar, hurricane, clifford shorties, but with the block milled .120 and a cam and ported head with oversized valves.