I was shopping for bullets myself the othr day, and was watching all the gel tests on the SP's. although some seems to have "some" possible expansion, they would always penetrate though both block of gel and couldn't get a recovered bullet. so I am not really sure how much benefit the SP's are over a spitzzer since they are both penetrating over 36".
if I had to choose, hornaday made a 150gr ballisc tip SST. cant be sure if it's still available, but I would think that would get some good reliable expansion/frag, maybe a bit explosive though
the 200grainers from wolf seemed to show the best initial expansion
https://www.youtube.com/watch?v=_wlIpqQUEM8
Winchester sells the 150gr soft point at a crazy price, but the results were about the same....on gel anyways.
I cant find the test ATM, but look around, its there somewhere. here is iraqi8888 testing various loads just so you can see whats out there, not a ballistics test though
https://www.youtube.com/watch?v=FTxqST9G6Xc
here is the SST
http://www.sgammo.com/product/hornady/20-rd-box-762x54r-hornady-150-grain-sst-ammo-80497
they also make a steel cased version that is cheaper IIRC
theres is no reason there shouldn't be effective hunting bullets for the 54r, I just think the market is too small for a lot to be invested in the r/d/marketing and tooling for high end bullets for the mosins. the mi surp is just too cheap to compete with. please remember that if your loading your own, your accuracy will suffer horribly from .308 diameter bullets. stay with .310-.311. slug your bore, you may even need .312 to get the most of yours, just depends, hey vary greatly. I just ordered the hornaday 174gr 7.7 with a diameter of .3105, not loaded yet, so I cant speak for or against, but that is exactly what my bore slugs at, so I may be better going with a straight .311, but we will see