Hi Don,
I think it boils down to your comfort level with the different choices. If the carby 400 can be done much more easily in terms of time & expense, that is probably the way to go. I'm very familiar with the new vortechs and aftermarket computers, and they won't make the botton end torque of your 400 without some mods. EFI (with the right tune) will get you better milage, but a 400 with really shallow gearing will get decent milage too. Do the math and gear for a cruise rpm of 1700-1900 @ 60mph. The low RPM torque of this engine is substantial. If you have used the 400 in anything you'll know what I mean. The newer chev engines include a 4.8 with only 10 or 15 HP less than the 5.3 if MPG is an important goal. They are cheaper too. Bothe 4.8 & 5.3 are iron block, AL head variants in the LS1 engine family. If you go this route, get the computer and as mich of the harness as possible from the donor vehicle. Then you will need to employ one of the tuners to disable some of the features in the PCM that look for hardware in the original vehicle which is absent from your truck (antilock brakes, etc). There are a nunmber of good tuners in TX. There is nothing wrong with persuing new horizons. I personally leave that for work, and use the familiar mechanical work to unwind and enjoy, but everyone is different. My personal choice would be for comfort and enjoyment while persuing my hobby. Where that lies is unique to you. Enjoy the journey and the end result will stand on its own. I hope that isn't too corny. Enjoying the ride is important. Life is tooo short to have your hobby irritate you too! <grin>
Mike V
