litin is correct.

On top of that, don't. Just don't try and build the 2.3 for more power. It is not worth the time/effort involved to do it. Even for "fun" or a "challenge" or for "just because" it is not worth it.

One option is to get a 2.6 and put the 2.3 carb intake on top of it. You are going to pay the same amount to rebuild a 2.3 as a 2.6 and you might as well put your resources into the larger displacement. If you are feeling ambitious, you could try and add the electronics to the 2.6 to get FI, but that is a nightmare amount of work.

With the 2.6, you can take an older block (pre-`93) and put a post '93 head on top of it. With the head (smaller combustion chambers), decking and boring the block you will get about 9.3:1 on the compression ratio. With some carb work/tuning, this should work well, especially with a Delta cam (you probably won't be happy with the CALMINI cam and a carb). Delta actually has a grind for carb'd engines. You don't need the pistons. Oversize replacements are available through any parts house for $35-$50 each.

If you are not wanting to do that, I would suggest sticking to a basic rebuild. Decking, milling, boring and balancing will make a nice running engine, but it will never be a powerhouse. The isuzu 2.3/2.6 blocks are much more torquier engines than HP producing engines. They are limited by their bore:stroke ratio and you just can't machine/build around that.

There are a few threads around, look in the Archives Forum, about working on the 2.6. Even if you don't go that route, the principles are the same, regardless of what engine you are working on.

Good Luck,
Michael

PS. I warn you. You are looking down a path that will cost you $1500-$2000 for a full and proper rebuild. At this point, on an '86 rig, you should also be considering finding another vehicle. For that price (plus maybe a bit more) you can find an '88-'91 Trooper with FI and have a much better base to work off of.