The 351 is a kick @ss engine...pull anything you hook up to.
You'll want to look at your bellhousing shape and bolt pattern. The question has come up before, and I'm not sure how it came out as in is it a chevy bellhousing, a BOP...or something weird.
The 2 pc shaft is fine. just install good components, and it'll last a long time. To do a 1 pc properly will cost you more than you'd ever want to spend. Most shops wouldn't even touch that, and 1/2 the ones that would...shouldn't.
Welcome to the board. If you have not seen this site on the V-6...you need to read it. Tons of awsome info on there.
http://www.6066gmctrucks.org/305V6.htm