IMHO, if you can get a good deal on the YJ, it will be worth fixing up (assuming it's not a rust bucket). We have the same 4 banger 5 speed set-up in our 93 and it has over 200,000 miles on it. It's good on gas and holds its own on the trails too! You can probably pick up a replacement core from a local junk yard or one of the Jeep forums.
Good Luck!