LS3 or 5.3L LC9 is the same thing in terms of size, just one is more money! I will cross that bridge when I get to it.
In the meantime what's great about these LSx motors is that you can get a 20lb plastic version with threaded inserts to mount an oil pan or accessories. So you can just pick up the motor with your hands and see how things are going to fit. Rather than constantly popping in the real thing back and forth with an engine hoist.
For reference: LS1 engine block at bottom of page here:
GM recommends, for the automatic version of their e-rod, to mate to a 4L65e trans which I believe is the same case as the 700R4 and a plastic one of those is here:
So I can do fit checks with these plastic things and then sell them on ebay when I'm done for probably 75% of initial value. Its like you are renting them if you can resell later.
Is the Tremec gearbox same thing as the T-56 manual 6 speed? I am not sure how the T-56 and the 700R4/4L60e/4L65e trans compare in size. Something to research. I was hoping to not have to pound out the tunnel, but again, when I get that point I will evaluate the situation and make a judgement call.
In my research prior to buying w108 I found out that the USA 280SE 4.5s have the same brakes as the w109 6.3 SELs. They use the vented front discs (not sure on the rear yet). Also, I've read some posts that some of the 4.5s have the same re-inforced rear differentials as the 6.3s.
As you know G, so many different problems to solve, so many things to learn, but for me, that is the fun of it. Thing is, I am not a fabricator, or welder, just a mechanical engineer who loves to build things and work on my own cars. This is biggest type of project I have ever planned to tackle but I know I can do it.
Thanks for the reassurance on the steering box thing, I was wondering about that.
All the best,