Mint condition '90 Cressida, engine damage, buy or no?

[NUTS]

Hey guys and gals, did a google search for Toyota forums and I found this. I am usually on full-size truck forums so have mercy

I found an absolutely beautiful, flawless 1990 Cressida, 3.0 inline 6, auto/AC blah blah blah, no rust which is rare in Hawaii. 147,000 miles on the odo. Did a carfax check and the title came out clean. (BTW, anybody need a carfax check let me know I have a week left on my account )

Here's the scoops: Lady said a friend borrowed it and overheated it. I looked at it and I opened the oil filler cap and saw the dreaded "chocolate milkshake" sludge on the cap. I don't mind changing the head gasket or the head, since I was an auto tech for 10 yrs, (converted to diesel and turf) and I can do that easily. My question is, have any of you ever seen a cast iron block crack from overheating? I personally have not but I have seen aluminum heads crack between the valve seats. I don't want to buy this thing and change the head and/or head gasket only to find out I have a cracked block.

Anybody know of a way to check for a cracked block besides the old block tester in the radiator cap with the greenish blue test fluid? This is the way I was taught to check if exhaust gases are in the radiator which is a pretty sure sign of a cracked block. Correct me if I'm wrong.

Sorry so long, thanks in advance for any help you guys can give me.

[Flashmn]

Nope, I never knew they cracked, I thought they just warped. Oh well, besides Cressidas have Cast iron pots as far as I know.