Here is an article on a 1st Gen Camaro which got a 6 speed donation. I only mention the 6 speed since you stated you will want to travel cross-country on trips. With plenty of 1000+ mile Hot Rod trips logged with automatics, 4 speeds, 5 speeds, and 6 speeds, I really like the 6 speeds.

Most of the population can do fine with 5 speeds because they don't drive as fast as I have been known to do. Personally, I like open roads and 80+ with the air blowin listening to some travelin tunes so a 6 speed comes in handy.

http://www.hotrodlane.cc/Instruction...d/6speed1.html

http://www.hotrodlane.cc/Instruction...d/get6two.html

As for the 350s, there are so many "reputable" producers of "turn key" engines...you will have plenty of locations to research. Here are just a few places to go look:

World Products - Bill Mitchell
http://www.worldcastings.com/

Edelbrock - Vic Edelbrock
http://www.edelbrock.com/automotive_...nes_main.shtml

Chevrolet Crate Engines
http://www.crateenginedepot.com/