Spacers aren't recommended for drag racing and depending on the track, not allowed. Your wheels are a +30mm offset and the widebody offset is 0mm for the D5's. This would mean if they would need to run about a 1.25" spacer.
To run that thick of a spacer it would actually have to be a bolt-on, hub-centric adapter. These are just fine for street applications but again, not recommended for racing.
USwheeladapters in Lubbock, TX uses high grade 6061 billet aluminum and the only company I would go with for spacers. Cheaper chinese options have been known to fail and this is where the bad press comes from on spacers.
My personal opinion: I know you want to sell them but I would tell the buyer to look for the proper offset in this particular application.