Just today I made up a pair of spacers almost exactly like yours out of 1/2" 6066 Alum. For the groove I drilled a pilot hole through the 2-1/8" cut before finishing that hole so that when cut out the spacer has a semicircle slot in it for the ridge on my stock strut. After cutting the 2-1/8" ID hole I put the spacers in a vise and reamed them with the 2-1/8" hole saw with 50 grit abrasive fabric taped around it, got me a perfect 2-3/16" ID.
My mechanic is putting these in for me next week sometime when my Moog LBJs arrive... My driver side LBJ collapsed this week but didn't separate. The 02 has 41k on it and had the recall done, heat shields and all right before I bought it used. Otherwise stock. I'd like to add another spring isolator pad to the rear and call it good as my 02 is prelowered. I just want to fit 245 A/Ts. I'll post after install.
Really great idea, forgive me for stealing it
Thankyou for sharing, sincerely