Welcome from the Pacific Northwest.
No big blocks in the Blazers. 350 was the largest motor available. Here are some specs on blazers -
http://coloradok5.com/specs.shtml#1972 (scroll down for earlier years.)
If that 2wd is a factory and has a cherry body, it is going to be worth a lot more than the 4wd. If you want to sell it, let me know. Post some pictures when you get them and please fill out your profile. You never know if a board member lives right around the corner from you and has the part or help you need.
Nice looking chevelle on your car domain page!