If you are impatient like me (or lack the skill to make some parts - again like me), Elm City has a nice selection of products for detailing engines.

If you are cheap like my wife (wait, that came out wrong), you can use any wire (inslulated or not) 24 gauge or smaller for wires/battery cables.  Beading wire works for fuel lines, tiger-tail or 43 strand beading wire works for braided line. I use crimp beads for fittings and spare wire insulation for spark plug boots.  Distributors are a b*tch for me to make, so I use premade, if I am going to detail to that degree. 

You can search for pretty much any part of the engine that is not box stock on SMA and find a way to either make it or buy it.  In the end, though, it all boils down to what you think looks right.  Test stuff out on engines in your spare parts stash (or buy a spare parts lot on ebay if you can find one with engines in it).  If you are happy with the results, that's all that matters.