I was all ready to convert over to this until I actually used the setup I already had.
My trailer is a 1975 model that came with the boat, just broke the original springs a few weeks ago. As far as I know it is the original setup and hardware on it. The former owners used boat hoists and not ramps to launch the boat.
The hardware for the bunks is the normal stuff you would expect.
But the rollers have a modification I had not seen before. It would appear they replaced the smaller rods and bushings with 1" pipe, it's strong and works very well for this weight boat, launches very easy at a ramp.
At some point I do need to tandem the axle though.
I've tried to look at yours to see if this is possible but can't quite tell if you have enough cross members to do it easily.