I'am looking to use bmw running gear and suspension, in particular early 2000 E46 parts, and having read some of the other threads on the forum this seems to be a bit of a no-go due to weight, size and wheel availability/choice.

My car isn't going to be a 'seven' style roadster so weight isnt a worry, but I have been having some headaches with regards to using the front uprights. They appear to be similar to the sierra versions, in that they would require a mushroom adaptor for the upper ball joint but no-one seems to make them.

Anyone using them or have any ideas on where to get mushrooms that will fit?

I don't think they exist.
But you can have them machined easy enough...
Just decide beforehand what ''drag link' you are going to use, as they are tapered and the taper varies between models/brands/...

Have a search for the later Marlins or the GKD legend as they use e36 and e46 donors iirc. There may be build diaries or even the build manual about.

I just measured an old e46 strut I had laying around.

The diameter is about 47.3-47.5mm. Maybe that helps looking for the right mushroom.

The wheel choice is rubbish due to 5x120 PCD, but you can redrill the hubs to 5x114 which gets you access to a good range of 15” JDM wheels. GKD (now DMO) use a modified upright which used a Transit drag link (I think) at the top, I’m sure they’d sell you a pair.

Rodgling, i plan to use standard bmw wheels anyway, so not too concerned about wheel choice. I will have a look at GKD though!

Thanks for that Ettore, i have a couple of early hubs myself but cant get to them yet as they are under a stash of other parts that I need to go through!