Another question about mounting diamond wheel

I have another question (see post Diamond wheel mounting issue) about mounting a 1V1 Diamond wheel in my Darex drill grinder. I have 3 Darex drill grinders, one I purchased new from Darex with all the available drill size chucks and 2 from HGR cheap without the chucks. What I'm doing with 2 of them is my customer is requesting another type drill point that requires split pointing and negative rake grind. Darex grinder can do one and requires another set-up to do the other. The other side will only do point angle grind. So if I grind the point and split point on one grinder I can simply use the other grinder that is set-up for negative rake grind while the drill is still mounted in the chuck.Sorry for the long and boring story as to why multiple grinders, the 3rd is for larger than 3/4" drills.
OK back to the question. To grind negative rake I found it best to use 1V1 wheels. As per my other post I received suggestions on mounting the wheel and eventually was successful being it was a wheel problem. This wheel requires a bushing to mount 1.250 bore wheel to shaft that measures .6245" in addition a spaced to move the wheel 3/4" away from the spindle face. I have a one piece bushing/spacer in the lathe roughed to 1.29" and ID .61". Slightly under 3" major OD is parted to about 1" X about 1/4" wide. I can now surface both sides of the bushing/spacer. Being size was recommended in my other post what would be ideal bore size to fit .6245" spindle and OD to fit 1.250" wheel bore? BTW this wheel is a General Diamond Wheel made in USA so I don't think I will have wheel issues.

Up-Date

Having to get grinder operational I bored the ID of the bushing/spacer .620" and used a 5/8 reamer to finish it. Turned the OD of the bushing to snug slip fit on the diamond wheel and faced the back side while still chucked then cut it off. Slight spot faced the cutoff side to 1.125 diameter.
Mounted wheel in grinder and it runs perfect!