When I bought my silvertop from SSS Automotive they recommended an autoelectrician that specialises in wiring up jap imported engine. I think they said he charges $500 for a 20v. I wired mine up myself but although its not that hard, if you're not used to doing that type of work it would be money well spent.
There is a fair amount of info available off the web but it took me a fair while to do it as I wanted to be really sure everything was going together right. I ended up unwrapping both my old 16v and 20v looms to figure out where everything went before chopping wires etc.
Anthony Kellam did an excellent job wiring my Silvertop into AE90. He works out of Brisbane but flies to Sydney to do lots of work too. He's on these forums. Charged me less than $500 too.