The caps on the Claw Law style tables are intended to reflect limited damage, so I generally don't apply whatever my 150+ rule is, until it hits 150+.
Like, if I were playing in a game with "wrap the chart" a 255 roll on a Large claw attack would do a:
135 result, then a 255-150=105 result
not a
135 and then a 255-135=120 result
Technically, core rule, you get nothing from rolls over threshold (either 150 on a regular attack, or 135 on a large CL attack) so it's a grey area where your judgment, the particular version of 150+ rule you use, and what has the right feel for your game.