Scotts has a bolt in ifs
http://www.scottshotrods.com/1955-19...s-bolt-on-ifs/
It’s top notch.
You really can’t go wrong with any of the modern IFS setups out there. The tubular A arms arm way better than the old radius arm setup. The spindle are forged steel, so there is plenty of strength there.
I have a 3600 truck with a long bed too. I’m using a Heidts crossmember and pro-touring spindles. I’m going to add an extra gusset to the rear of the crossmember. I’m confident it’s more than strong enough.