I make my 500-450 #2 from 50-90 brass with very little effort just easing it in stages into the sizing die using Imperial Wax.

I use Mag-Tech 32 gauge hulls to make both 50-70 and 43 Egyptian.  I load .451" bullets in the 43 Egyptian.
After first annealing I trim the brass to length for the 43 using a 50-70 file trim die adjusted to correct length. That also starts the first neck step down from 32 gauge. Then an RCBS FL die for 43  Egyptian is used in steps to the FL sizing of the case.  What I end up with must be similar to what you need because as stated I am loading 45 caliber bullets in the 43 Egyptian. 43 Bowmont dies should also work since 43 Egyptian cartridges can be fired in 43 Bowmont rifles .