There is some profiles on rig exchange that was made using Rammfire vst, and that is modeled after richard's pre 500 dual rectifier,
I have not tried the profiles myself, but they might be interesting for you?
Search Rammfire on exchange to find them.
Here is youtube video about it.
http://www.youtube.com/watch?v=ApLHCbQ3gnw
Product
http://www.native-instruments.com/en/products/ko…uitar/rammfire/