What is your club authorised up to energy/velocity/calibre wise?
Happy days then mate. Well since you don't have to worry about max energy down the range and since you aren't trying to justify it for uk quarry (like many do with 375) why not step up from a 416 or 423?
I'm not saying get a 585 Nyati but I'd be leaning towards a 458 (450 Rigby?) as I bloody love mine, maybe a 470 Capstick or 500 Jeffery just to up the ante.
Ps I appreciate the offer but my 45 is approved for UK quarry so I don't target shoot much except on my permissions.