I have limited experience with 450 GR’s, I’d have to ask a few questions.
Have you got pics of the 450 primary? The basket your spot in with, grind heads off rivets, kncok the centres out and tap with the necessary size. Pretty sure 1/4” is to small though, pretty sure I used 5/16” on the 300.
98 300 Fourtrax 4x4
Custom built mud bike - Now sold.
2004 Foreman 450S
Fully overhauled (nut & bolt rebuild), 2 lift kit, 28 mega mayhems, ITP delta rims, ES floorboards, 22 LED lightbar, Pyle Bluetooth sound system.