I went through this same thought process then scored a $400 LS1 and a $100 4L50E trans so my decision became very easy. Then I dumped about $3K into the LSX with a SLP head/cam/injector package and another $600 or so on the short block for rings, bearings, gaskets, double roller chain and oil pump. Dropped another $600 in the trans for a 2,800 stall TCI converter and got the internals for free from a buddy for a full rebuild.
Harness cost about $300 (painless) and I scored the computer on ebay for $120 (new in box as a GM performance PCM). Found a fellow in Indian that re-programs for $75 plus shipping. Did the headers on the CHEAP by getting a set of Pacesetter 2000 Z28 non-emission units. The passenger fit right out of the box. I also put a Steeroids rack in so I had to move THREE pipes on the driver header. Topped that off with black ceramic coat and I am good at under $400 for the headers complete.
Motor mounts from Brewers Performance with stock F body accesory brackets and a custom A/C bracket from Brewers to run the Sanden compressor. A/C from vintage air.
Radiator is a 31" x 19" mated to a late model Malibu fan assembly. The PCM controls the fans neat and clean.
If I had to do this again I believe I would have left the motor more stock as dealing with some idle issues and the excessive (sewing machine) noise that comes from the engine with the head/cam swap is a pain in the butt. However, when you roll on the throttle is is AMAZING!
If anybody can do things on the cheap...I can. This should give a feel for what a DIYer should expect with some eblow grease and creative thinking.
See more on my website:
www.mcspeed.homestead.com
Good luck with your decision!