I'm looking to pro street my '66 but have no experience with chassis mods or fabrication. I have been looking on line at the Art Morrison ladder bar complete kits because they are a local company to me, but would like to know some other options too. What are some of the challenges I should expect and what companys products have you used?

I was thinking a ladder bar for ease of setup and keeping the back seat in the car. I plan to drive it often in the summer months when done and hit the local drag strip on occasion. I would like to find another solid '66 frame and add the kit to it myself and have a cert. welder friend do the welding. Is this something a back yard mechanic could tackle?

Yes. Lots of usefull information here as well from others who have done it. I personally chose to have a shop do it... (you may/should consider this as well and make the big list of all the other things... including your time... weekends.. etc)
For example:
Will you stretch the quarters?
New rims,
tires...
housing..
axles...
brakes..
fuel cell..

... oh and will you tie in a roll bar? or cage?
..
AND.. how about an anti-roll for the rear?

I have done 2 backhalfs in my garage. One was a 77 vette that I used a Morrison kit on. Came out great, but unfortunately the car was stolen.
At present time I am doing a 67 GTO that I am using a S&W race car kit on. If you check out my site you can see the progress. I haven't added anything new to the photos in about a year so it is further along. Both cars had cages and fuel cells. On the vette I didn't need to do any work on the wheelwells. And the GTO I pie cut the ends of the wheelwells and didn't need to stretch them out.
I welded the vette up myself with a 110 welder and the second one I had a friend that is a certified welder do it for me. He owed me a favor.

Take it to a pro and get it done right the first time.It's not the kinda job I would tackle first time out.

A lot of things have come up in the past year that prevented me from seeing this through, and now with cut backs at work happening it may still take a long time to finish. I located and purchased a '67 el camino rolling chassis to build from. It was cheap and should clean up well. I also figured it would be a good start since they are some what boxed to begin with, just picked it up last weekend. I'm looking at the Art Morison back half ladder bar and buying a drop out from a friend for the 9" rear. I found a local chassis builder and Chevelle fan to help get it set up and welded properly when the time comes. It may take me the rest of the year to save and buy the axles, wheels, brakes, and tires, but I'm determined to have a pro street. Thanks for the advise/help!
http://i67.photobucket.com/albums/h293/66ssfan/66chevelle/001.jpg
http://i67.photobucket.com/albums/h293/66ssfan/66chevelle/004.jpg