BBC swap questions

[sls_06ion]

I'm kinda new to the forum, and kinda new to playing with old trucks, playing with sport compacts for a few years now. I'm fairly familiar with these truck as I've been doing quite a bit of electrical work, HVAC, and audio, plus I can turn wrenches too. Now to my questions I've been give a 454 and a th400 tranny they have 37xxx miles on them don't smoke no blow by, tranny shift fine so it can be done with a little cleaning of pair - now the harder part, I've got a 66 GMC 1/2 ton 2 wheel drive--351 v6 and a 4 spd manual. I'm curious as to what parts I may need to aquire to do the engine/tranny swap. I have a set of motor perchs for a small block, are these what I should use? and since I have a manual tranny currently, should I order something like the CCP tubular tranny cross member w/ prothane style mount? Does the firewall need to be "manipulated to fit" a BBC? What kind of shifter has anyone used after a swap like this, as I currently have a floor shift?

Any body have any helpful hints or suggestions?

I'll try to update this post with some pictures later on of the truck and engine bay.

thanks everyone, Tony