I can't comment on the LHD 510's, but the RHD 510's in australia it's as easy as the following;
reverse the crossmember (this means reversing the whole crossmember to accomodate for the rear facing sump, as well as reversing the control arm pin holes as 1 side is tapered)use standard S13 SR20 engine brackets add 10mm spacers to the exhaust side bracket and BOLT in the engine
For the gearbox mount, use the S13 gbox mount and drill new holes in the floor.
You will also need a custom sway bar, and on the RHD model you need a reversed steering drag link.
Since all your steering is on the left side, you'll have to work out the exhaust manifold stuff, this is where I'd look at the mesojdm thread for ideas.
Alternatively you could buy a pre-made kit from australia and get it shipped over, some places below that can help;
http://www.datsport.comhttp://www.swmot ... dat.com.au
Good Luck.
Modified by Godzilladat at 9:59 PM 11/5/2007