Progress at last...

After non-trivial searching for parts, I settled on mower blade, adapter and pulley from the same Deere series mower that the engine came from, a JS46.  I ordered them online as that is way cheaper than visiting the local dealer (sorry).  HOWEVER, what wasn't clear is that there was a serial number breakpoint where the blade & adapter changed designs.  I ordered the correct adapter, but the "cheaper" blade had to be exchanged for the right one.

The earlier blade only had one hole, the newer one has three as shown above.  In the diagram (from partstree.com), I chose the 0050 pulley and the 0110 blade adapter to fit.

This is important as the blade adapter mounting surface is 0.9 inch lower than the end of the shaft, and the blade itself has the cutting edges even lower again.  This results in the cutting plane being 1.65 inches beyond the end of the shaft.  This folds back into the deck design and defines the height of the motor mounting with respect to the lower edge of the sides.  Now that part can progress forward.

Additionally, I acquired a Spektrum DX7S radio and AR8000 receiver.  Local purchase at Performance Hobbies in Webster.

I was going to get relays from the same place I got the motor controller, but I need at least 3 channels ( I ordered 4 ).  They wanted about $25 each, so I looked around a little more.  I found Pololu ( same place that makes all kinds of stuff including some of the original RepRap motion control ) had some nice units for under $10 each.  I also scored some RC servo cable extensions.

These relays will control the engine start and kill switch plus the motor brakes.  These modules interpret the RC servo pulses and turn on the relay at a certain threshold.  At this price, it isn't worth making anything.  A very rough draft schematic is below.

I am looking at circuit breakers and will probably use a Bussmann 70A switchable unit, which will double as an "off" switch.  I may also add some automotive self resetting breakers here and there as I worry about melting things sometimes.

Still working on tooling, the Y axis DRO is getting closer.  The encoder mounting plate is done, and working on the bracket for the read head.  The new vise is installed and trammed in, what a difference that makes in setup and repeatability!