New with a question

Hello to all. Just joined up here and hate to start off with a tech question so I'll say a little about myself first.......I'm a musclecar fanatic, a horsepower junkie, and have been a mechanic all my life. I'm 54. Enough about me..I just picked up a 66 notchback in need of finishing as a father/son project and maybe one of you guys can help refresh my memory. It's an original T code car that now has a fresh 79? (D9AE) 351W with all the good stuff. Also has a 72 C6. This car has sat unfinished for about 8 years so the first thing I wanted to do was prime up the engine and fire it to make sure all is good before I continue the resto. My plan was to unbolt the converter and push it in so the trans (dry and no cooler lines/fill tube/driveshaft) installed wouldn't turn and possibly be damaged. Well, the converter will not push in far enough to disengage the studs from the flexplate. It's about the thickness of the flexplate it would have to move to disengage as all the way in the studs are about flush. Sorry for the long explanation but my question is should this engine/trans combo have a block plate between them? It doesn't and if I remember correctly all? used one whether auto or manual? I did an internet search and got about a 50/50 answer so I'm more confused now. Thanks in advance for any info.

Thanks for all the help guys. Seems this forum is more geared to the late model Mustangs ? but nonetheless if anyone is doing a 351w in a 64-1/2 thru 66 feel free to pm me if you run into a wall trying to make things fit. Aside from having to fabricate a trans mount and E-brake extension tube I managed to fit a 351w with a C6 and full length headers in to a 66 with absolutely no clearance issues that will haunt me saying knock knock or binding. Ended up using mostly shelf parts that some need "tweaking" and some just laid right in. All in all it was a time consuming swap to make it (perfect) as far as looks and fitment but can be done rather easily. Only reason I'm posting this is when I was doing a search on the same all I found were unanswered questions. I have lot's of answers I'm more than willing to share so....Be glad to help if and where I can.