If it were me, with the component shortages we’re currently experiencing, I’d likely try to move those bullets on and use the funds to buy more appropriate bullets or a bullet mould.
On your question of whether to buy a 45/90 levergun - well, it’s a very capable cartridge. The twist rate of the Winoku rifles is 1 in 20”, so they will stabilise any sensible weight 458 pill (including 500+ gr). You can use most pills suited to 45/70 use, but Its main advantage over a 45/70 is the additional capacity to drive heavier bullets, especially if you like using cast bullets with lots of lube grooves. However, the curved steel buttplates that Winchester seems to fit to their 45/90 rifles might temper your enthusiasm for heavy loadings. I much prefer a shotgun style buttstock on a firearm that has heavy recoil.
