Off- Center M@A problems?

[TurboMike]

Took a Stage II off-center engine and put in another GN. The guy bought the car not running. The person that had the car said it ran ok, but the DFI was outta wack. I pulled that engine and put in a nicer body. Rough idle, engine miss... cylinders #2 and 4 have about 25psi of compression. I did a air test and it seems air is coming out the exhaust. Where these heads known for cracks... if so where? When you get under some boost it smooths out pretty decent which acts like a valve not seating. I checked and they aren't too tight. With it being two cylinders side by side it makes me think headgasket, but this is car hasn't been ran much. The heads are from the mid to late '90's. Any thoughts?

 

[Mac in SD]

Those heads had some porosity problems, and I understand some core-shift issues, too. I know Fred Avery had one heck of a lot of water seeping into an exhaust port on his M&A heads...actually filled up the valve pocket to overflowing in about 5 minutes. K&W took care of it though.