Would I be stupid (replacing stock motor)?

[Gary]

I'm about THAT close to going monday and picking up a sweet 86 Silverado, the only real problem it has is, it has a weak 305, it has OD, AIR, the body looks like a 2 or 3 year old truck, not a 20 year old vehicle at all, interior is very nice, just an overall peach.

Well I have that pretty damned strong 402BB in my 72, and it should bolt right up to the 700r4 the 86 supposedly has(?) and it also has A/C so I should be good with that, question is, is keeping the truck with the original motor THAT important? Was O/D an option back then or has the tranny already been swapped?

What would a swap of motors require and what should it cost me? I'm no mechanic at all.