I needed 1 1/4 inch standoffs and had Roger give me 1/4X20 on the firewall side and 10X32 on the mount side. I should have had him thread the whole thing at the 10X32 because of the shortness of the standoff and used the entire threaded area for the 10X32. Having him thread in both directions only gave me 3/4" bite for both bolts. I don't have a DA but you need to find out what size hole is in the motor mount and I would suggest you use that size for the motor/mount size (probably 10 mm but I'm not sure) and go with the 1/4X20 on the fire wall side.

For all you guys out there, this is only my opinion and suggestion. I CAN be wrong but based on my experience with Roger's standoffs, this is what I would do.

I hope this helps.