I went through this a couple of years ago. I had a 73 cast crank 340 that someone went over to a 1970 forged crank. But kept the 1973 cover. I may be wrong but the change happened to the covers when they went to cast cranks. The harmonic balancer marking was 90 degrees off from top dead center...
Mid-Atlantic Customs in Maryland has done 2 E body convertibles for me. They are excellent. Both took around 6 months to get through the shop. They can be found on facebook. Excellent body and paint work and mostly MOpars.
I used a J hook bolt that was a half inch longer for my last heater box install. I also have a tool box that is almost the same height of the heater box. So I stick that under the box for removal and install. So you are not trying to muscle it in and out.
Have you ever operated a manual top? The manual top pistons have springs in them. So one person can easily put the top up and down. I have both manual and a hydraulic top E-body convertibles. To me they are both easy to put up and down.
Dante’s is actually my favorite supplier. I’ve been buying from him for years. My interior is a mix of nice original pieces and the rest from Dante. I would definitely buy the interior kit from Dante if I needed everything. I will say that there has been a huge lead time in legendary interior...