nytrdr24
+1y
sorry about not seeing this any sooner, and welcome to the bscene!
So I get we can rule out the weber swap lol, it would be kinda hard to
install & still keep the emmisions stuff...
Ill have to check when I get home from work, but I know there is an idle control valve on the 22k & 26k carbs, that may very well be your problem, but as I said, I'll have to check my chiltons when I get home so that I might point you in the right direction, heck I might even be able to scan ya a copy of the exploded carb diagram (at least i think there is one in the chiltons) & I won't even ask for a pic in extchange j/k lol.
as far as one of your other initial q's, there is a guy either on cardomain or ssm that was custom making headers for the b26k's, I know I've seen him sellin some on e-bay every-now & then, you could see if these guys in austrailia would ship ya one
might also want to check with carl at he might be able to get or make ya a header for it.
option on the cat is either to gut it, or have a short piece made to couple inbetween the mani & the second cat, probably wouldn't cost too much to have one made, i see your in massachusetts, if you can't find someone close to make ya a coupler pipe, check with , I think the guys name is phil, they are located up in your neck-o-the-woods, & do make custom stuff from time to time, & he might be able to help ya out.
I know it can be agrivating sinkin a bunch of $$ into it and it keep giving ya trouble, but don't give up on the ole winter beater just yet, they (when running properly) make a decent truck, I had a bud back in the day that had one like yours & we put it thru some of the roughest terain out there & like an old john deere tractor it just kept pluggin along!
if ya need n-e thing else don't hesitate to ask.