Standoff size for Mini-onslaught

[Rare blade]

I am trying to figure out the standoff size i need to replace the plastic backspacer on the mini-onslaght to make it more like the limited edition one. Within the plastic backspaced there are are nested tubes but they don't hold the liners in place tight.

Not sure if this is allowed but I think this is the style I need
http://www.knifekits.com/vcom/product_info.php?cPath=60_91_243&products_id=2623

The blade thinkness is .114" and therefore I think i need .156" standoff, any suggestion or direction would be appreciated.