Switch to a 2.5" thick core but overall a little bigger than the mouth of the bumper. That will leave a little bit of a lip on the mouth while filling the whole mouth.
Was only a half grown Roo, about the size if a Great Dane, put it this way, it didn't feel it, but i did sure did.Core Size 600 x 300 x 80mm (24 x 12 x 3 1/8")Wonder whether a JDM crash bar and bumper would be a straight fit onto a USDM 8G !
7g crash bar is Hellahuge.lol I dont know if it wold work behind the 8g jdm but I do know that it wont work for the 7g jdm.