Doing some LS swap homework

[Suburban_Tyler]

I'm sure LS questions are getting worn out. LS engines swaps are brand new to me. I'm interested in the how to's and peoples experiences and advices. Not so much criticism. What I have is a 1990 GMC R1500 Suburban. It has the tbi350 with a 700R behind it. The odometer shows 235,000. It still runs great but like all machinery, it eventually just gets worn out and tired with time. From what I have been looking at is a brand new engine with a controller and transmission with a controller over a salvage yard engine/ wiring harness/ ecm due to leaning towards a 6.2 and I don't know how much of a pain going through all of the wiring will be out of a used set up. I just think its more of my cup of tea. So I have a few questions that I will break down into sections. Just doing homework at the moment. I haven't bought anything yet.

1. If I was to buy the LS376/480 dbw that GM Performance offers with the engine controller, how difficult will it be to get all of my factory gauges including the check engine along with the battery light hooked back up? Anybody have a link to a wiring diagram for the 1990 Suburban?

2. From what I can tell the LS376/480 has just a single fuel line rail without a return. I assume I would need to do a corvette style fuel line that has the return on the filter? Correct me if I am wrong. What do I need to do with the pump and sending unit? If the return line is before the pressure regulator, how does the pump keep sufficient pressure to the regulator? Is the some sort of regulating in the filter? "I think" I read where somebody used a late model pump and replaced the factory in-tank pump with the higher pressure pump. Would the sending unit lines and flow enough fuel for the engine?

3. As far as a transmission goes 4L80E or 4L85E with a controller. I think my 700R is an electronic version with a electronic speedo. I don't ever recall seeing a speedo cable not that I really paid much attention every time I've been under the suburban which is usually only for oil changes. How much of a pain is it to get all of that stuff working and I would also like to get the cruise hooked back up. Anybody have knowledge with that? I know there is a FAQ with the cruise but I just didn't see the answer I was looking for. Or maybe I did and just don't realize it.
Thanks for any knowledge you can drop on me.