The VHII neck splits well, so that would be a good choice. I have a Black Dog neck but have not set it up for coil splitting.
I am not familiar with the 498 but I assume that the Black Dog bridge will be slightly lower in output - it is not as powerful as the 9.4 DC resistance suggests. The VHII bridge is in fact slightly more powerful. Have not heard either of them split, though.
The Crawler, Holydiver and Abraxas all split really well. They should be in a similar power range than the 498.
As regards the active preamp: is it set up to boost the pickup signal or only to buffer it? If it boosts the signal, lower output would be beneficial in order not to overload the amp when you don't want it. The downside would be that the lower output you go with a humbucker the thinner it will sound when split.
Cheers Stephan