AMY - I have to agree with NIC B. NONE of us old timers had used that method of repair, we always did it the hard way. GREAT JOB! That's thinking "Outside the Box!"
FRANK - The Hydro's used the steel dowel pin, because only one 1/4" dia pin drives the whole tractor.
While I agree with Jim D. that spirol roll pins are much stronger than a normal roll pin, I think both my GD's have just normal roll pins in the clutch plates that are decades old with no problems. The rear pin just transmits half the torque of the engine, the frt pin transmits the other half plus holds the pressure of the clutch spring. If you want to make sure you won't have a problem, I've run smaller roll pins down inside the 1/4" dia roll pins before. Spirol pins can be really hard to find some places.
The Hardware binder followed me home from one of my purchasing jobs years ago. It has ALL KINDS of spec sheets on specialty hardware and Timmerman clips, roll pins, etc. It's a full-size D-ring binder about 4-5 inches thick separated by MFG's.
I also agree on the greasing of the driveshaft, just attracts dirt which makes a dandy abrasive mess, and if a bit of grease gets on the clutch plates will cause clutch slippage. AND NO.... I was not out greasing my drive shafts.