8 minutes ago, Van Quixote said:

I appreciate your help and input, Bennie.

As was told to me, the PO contacted the company that did the rebuild and they felt that the issue was with the valves and had the PO tweak the valves.  The PO got it running, but decided not to continue tweaking it (due to unrelated life-based time constraints that left him no time to work on it further) and just went out and got another rebuilt engine. So the PO unloaded the engine cheap.  Along with whatever valve/compression issues come along with it.  Ignorance abounds!  Haha.

I don't the performance gains are worth the effort with the 22-heads. The 2.5D/2.2 heads combo just isn't that impressive unless you spend the money for cams, and exhaust.  If you do try and mate the with the 2.5 SOHC block, the performance is unknown... Also, which headgaskets would you use? The cheapest route would probably be to just keep the waterboxer in place and enjoy it for what it is... But in my opinion, after having done many different motor swaps, the time and money can be wasted if you cut corners... I don't think you have the right components to mate for a frankenmotor. I think you either need to find a 2.5D block for the 22 heads, or 2.5D heads for that SOHC block. OR, just figure out what is wrong with the SOHC long-block and fix that. It's not an impressive motor, but it will work well, and I hear the SOHC heads actually flow pretty well. You can pop the heads off, and fill the intakes with water to see if there are valve issues.. There are plenty of videos on youtube that can help you determine if there are valve issues... If none of them are problematic, then you'll know if it's the block. 

The SOHC block and DOHC heads is a great motor. The DOHC block with 22 heads does come with a power improvement over stock as well, but it is limited. You may need to call around to different Subaru specialty shops to pick their brains and see if your combos can work. 

https://forums.nasioc.com/forums/showthread.php?t=631527

https://forums.nasioc.com/forums/showthread.php?t=2220331

 

Also, I suggest PMing 86Bratman. He has built a few frankenmotors, and would have helpful information. He gave me great advice when I built my 2.5 SOHC block/2.5D Head motor. 

 

Good luck.