Replaced Dash Harness - truck wouldn't start

[lks dcvn]

So I was feeling ambitious over the weekend and replaced the dash harness on the Blazer...

Got the old one all out in one piece and then when I installed the (stock) replacement (used non-cut full gauge harness) the truck wouldn't turn over...nada - no click - nothing.

It does have a HEI ignition - but I thought the wiring was changed in the engine harness to make that operable...not the dash - guess I thought wrong. When you look at GMCPaul's site - it doesn't say that you need to buy a dash harness with a HEI distributor...

I ended up taking out the wiring and putting the old stuff back in (it started with the old wiring back in) to get it back into the garage...

What should I look at between the two harnesses to see what needs to happen to get this 'newer' dash harness installed? The wiring on my Blazer works well - it just looks like colored spaghetti under the dash and I would like to clean it up.

I also broke my plastic oil pressure line fiddling with the wiring harness... and it sounds like I have to replace it instead of fixing the end that attached to the gauge.