This has been pushed into the backyard while a whole bunch of other things happen in my life, but I have bought a few things for it, like a rollover valve for the fuel tank.
But I have mostly been ignoring it.
Inadvertently, I made progress…
I bought a set of 15x7 Performance Superlite wheels cheaply a few weeks ago … but couldn’t pick them up until earlier this week due to broken arm shenanigans.
They were supposed to be 4x114.3 stud pattern and +30ish offset. This meant I could use them on a number of different cars…
Except they turned out to be 4x108 and +12, which is a lot less useful. The offset means that adaptor spacers aren’t a viable option.
After a bunch of head-scratching, I figured that 4x108 is a starting point to convert them to 5x108 and then they can be used on one of the 240s.
So anyway, I spent ages trying to work out if I can mark them up accurately enough.
Short answer is yes.
After a bunch of messing around and not being happy with the results, I machined up this spacer to find the centre of one of the stud holes (yes, “Spac bought himself a lathe” is probably going to be a recurring feature for a while now… 😆)
Having a stable, reasonably accurate centre is one part of it, but having the centre at the same height as the mounting face also improves accuracy.
The other big step was to have a measurement from one stud to the “opposite” stud AS WELL AS the measurement to the adjacent studs. 
So yeah, I reckon I can find the location of the holes to convert to 5x108.
Next task will be to work out a way to drill those holes accurately… without just buying a milling machine…
