Not sure if this will help you but I put a set of Mules in my old SG1500. I was really happy with the results too.
BUT - I did put the old ones back in after a while. Don't get me wrong, the Mules were really, really nice, very open and had a beautiful singing quality. It's just the stock Yam pups from the mid-70's were absolutely smoking. They sound tight, and very powerful compared to the Mules. Almost like a different sounding guitar altogether.
Just my $2 worth but if it was me, I'd stick with the stock pups. Mind you, I'm not sure how the SG1500 compares to the SG2000 pickup wise. My SG1500 was from around 1976, not split coil, so was more like a Les Paul, and I'm not sure how those pups compare to the 1980's SG2000 pups.
Or you could stick some smokin' BKPs in there!!!