The 181 is basically a 153 bored and stroked. The bore went from 3.875" to 4" and the stroke from 3.25" to 3.60". The main bearings are the same but the rods have a 2.1" crank pin instead of 2.0". The bottom end is stout with 5 mains. It should handle the same amount of boost that it's big brother L6s do, maybe with its shorter crank a bit more. If there are the kind of caps you mention for the L6s they will work on the L4. The late 181s have one piece rear seals and some have pressed powder rods. The 181 rods are one offs and don't fit anything else. They are the same as V8 rod but are wider on the bottom end. There are at least 3 181 heads two are 8 ports and the best one has 2" intakes and 1.6" exhaust. With 30 pounds of boost it will flow. It will make your old Scout a little beast, better stock up on axles.
