I do not have access to a welder - I sold off my welder when I had to relocate 3000 miles North from Texas to BC Canada.
The Bestop uppers I have are the 51780's - after I spoke to Adam at 4wheel parts - he told me that you are right, the TJ uppers can be modified to fit, but with no welder I am kinda ***** out of luck. And these uppers will not fit. I have to ship these back, again I am without the Jeep - and here in beautiful BC, it rains like a mofo most of the year.
And what about the bottom, do you remove the channel from the YJ doors?