The Painless harness made life a breeze. It all pluged in directly to all the GM sensors, injectors, relays, etc.
As far as my install time, it took me 2 months. I only had time to work on it after work some nights and sometimes I didn't work on it at all for a week or two. The hardest part was the fuel system splicing for me. I had to install an external pump 2 filters and route some new lines. The wiring was a breeze. It took a couple hours tops.
If I had to do it all over it would be a couple days of good hard work on it. When I started my swap I didn't know enough about the system so I was trying to learn as I went which is the WRONG way to do it. If I would have done the learning part of it first it would have been easy. There is alot more experience people on here now that have alot of info I could have used when I started mine. Thats life though.
As long as you have good skills in the mechanics area and a decent head on your shoulders then it shouldn't be a terribly tough swap. The worst part for you will probably be dropping the motor and also dropping the gas tank to get to the fuel pump.
Harley