I tried to check that link you posted .. alas, I get a message statin' that I cannot visit it ..
Now .. what to pay for a Jeep? How much money do you have? How much are you willin' to pay for it? If you are looking for a non-running project Jeep, a $1000 - $1500 price tag would be about right .. as long as everything is still there .. missin' pieces could lower the price.
A running Jeep sells for $3000 to $10,000, depending on the options, miles, condition, etc .. pure stock in perfect condition Jeeps command a higher price than highly modified ones .. the modifieds are harder to sell because there are fewer people interested in somebody elses project ..
Now, as far as the Chevy 350 motor .. it didn't cost me much to swap it into my rig .. just time and the time of some good friends. A CJ5 has some length considerations to work around, but can be done. The CJ7 is easier to swap the 350 into, but there is something about the CJ5 that is way too cool.
Have you considered the rare CJ's like the 6 or 8? They are both longer versions of the 5 and 7 (respectively) .. but I would really look at finding the 6 to restore and baby .. awesome lookin' rig