One of our sponsors BRP ------->
Sells the motor mounts and tranny crossmember 4L60 and T-56 for the swap.
On the headers from what I've read most our building there own. Of course any kind of header in a Duece is going to be a challenge. If you can get past that everything else should be pretty much cake.
That is going to be an awesome ride. I've always wanted a 67 Chevy II with an LS1. Good Luck with the swap and keep us updated.