I think William summed up the three most important points of this conversion: thoroughly flush and clean, use ester oil and pump down thoroughly, preferably with a wet vane pump. The lab pumps like William is using are outstanding, but expensive. I have a wet vane pump meant for refrigeration service. It is not as good as a lab pump, thus, I feel that 24 hours is the minimum for my setup.
I bad mouth the conversion because mine have not worked out well. That doesn't mean that they all will not work well. West Texas is dry heat, the Eastern part of the state gets pretty humid, the coastal part is only one step away from swimming through the air.
If I had a practical way to put in a bigger condensor, the 134 would probably work out pretty well for me.
Have a nice weekend,