read this afternoon about off center rear uprights and its possible effects on twisting the upright managed to find two pics, first is from a avon however I have seen an early striker with a off center top bone mount with a side mounted coil over.

The second is from the mid engine Devil.

Don't think either have suffered from "twisting" as there still being used today.

Hope is of some use.
Rescued attachment HPIM0591.jpg

Image deleted by owner

Thanks joolsmi16, it was me who posted the question today. From what I've seen so far, I'm much happier that there's no issues and that devil one is very close to the offset I need.

Thanks again