Mike,the plates are usually available on Ebay,and some old truck vendor's like Jim Carter have them.
From my experience,it's a good option if fan location is important.It's easy to do with the engine on a stand,as you must drill and tap a few holes in the block.It does require a little engineering to get the pulley ratios and belt size correct.
All this only applies to Chevys originally equipped with a 216 or the 54 235-261's.
I used a 60's Falcon 6 water pump pulley on several situations.It did require enlarging the center hole in the Falcon pulley,spacing the pulley to the proper position etc.Some guys just use a smaller 216 damper on 235-261's,but I felt it was best to use the proper sized (weight) damper.
John, I like using an after market paddle blade flex fan,the blade can be easily trimmed for damper clearance cause of the deeper pitch on the blades.And the flex fans are rated for 8000 rpm fan speed,no worries about 50 year old fans flying apart from overspeeding.
But there are some guys using short water pumps who report no cooling problems,I think this all depends on how the engine is tuned and how the vehicle is driven.
Or just use an electric fan if the old school mechanical fan isn't important.
