If your goal is for lathe turning tools, then your platform is not wide enough between the two side panels. How can you sharpen the skew?
If you use the platform alone, you may need to swing your tool (such as side grind bowl gouge).
You will have to modify your design to move back the pivot point and round off the top of the two vertical members.
This is a popular design that works.
It is what our club grinder has been using. This is a home made version of the Oneway Wolverine.
The gray wheel that you have is hard and durable but not ideal for turning tools. The steel shaving embedded into the wheel is likely to glaze and overheat. You will need to dress the wheel very often.
It is better to use Aluminum Oxide wheel that is friable; the wheel will constantly break down, exposing sharp surface to continue grinding. Softer wheel will run cooler but will wear out faster. The best is "J" or "K" hardness. I like "K" better because it holds up better.
Does the out board side of your headstock spindle has male or female threads? If it has male threads, then you may be able to drill a center hole in the handwheel for the knock out bar to pass through without removing the handwheel.
Inspect and clean the mating Morse Taper. If both are in good shape, a hard tap with the knock out bar should remove it.
Or you can screw on a 1" X 8 tpi nut on the spindle before you put on the spur center with wider shoulder. You can back off the nut to force the spur center out.