I see that your current bike is a swing arm model. I know a bit about plungies and very little about SA models so my advice may not be any use to you; however here is my post from a few years ago:
I bought a Norton 850 oil filter head and filter from Ebay intending to fit it in the toolbox of my plunger frame GF as others have done. However, the assembly was too wide to fit in the toolbox so I have mounted the filter on the rear mudguard behind the gearbox using nylock nuts. Both parts are dull black so fairly inconspicious.
When mounted the filter head union stubs point towards the chain. I've used Goodyear 8mm, (5/16") ID reinforced rubber pipe to do the plumbing.
The oil feed pipe from oil tank to pump union pipes is as original. The return from the pump is carried over the top of the gearbox, down between the vertical frame tube and the gearbox then gently curves around to meet the filter inlet stub. The filter outlet pipe is routed tightly underneath the gearbox and then up behind the pump union assembly so it appears adjacent to the original metal pipes. It lines up nicely with the rocker feed banjo and oil tank connector. Finished off with proper hose clamps it looks neat and not too obtrusive.
Here is a link to some photos of the set up.
http://tinyurl.com/cqbbnj7Update: I've added an annotated image to show the pipe runs.