Hey guys i am looking at picking up a van thats newer with the 454 and what would i have to do to keep the fuel injection

Actually not a tough swap at all :)

If you have the entire running van, then you will have everything needed to swap it over to your truck less the VSS. The VSS (Vehicle Speed Sensor) will cost approx 50 dollars from Jegs or Summit, and goes inline with your speedometer cable with your current transmission. The other option (if you have a 73-87 truck) is to use the tranny that is behind the 454 right now, and swap to an early 90's burb / blazer electronic speedometer. If you go the way of the electronic speedometer, they can be had cheap at a wrecking yard, but be sure to get the correct DRAC for it. I cannot remember exactly what DRAC stands for, but it basically converts the signal that your VSS produces (either 2 pulses per mile, or 4. I am 90% sure that TBI is a 4 pulse per mile setup) to the correct signal for the speedometer to function correctly. The neat thing about this is that you can modify your DRAC with a dip switch board, and change the switch positions to change the signal going to the speedo to account for tire size changes etc, rather than changing the little gears in the tranny.

If you have / are getting a custom exhaust setup with headers, you will need to install an 02 bung into one of the header collectors. Depending on if the exhaust gas is too cold by the time it gets to the collector to heat the sensor up enough, you may need to install a heated sensor. They are a bit pricier, but are worth it, becuase a malfunctioning 02 sensor will cause a messed up mixture. Otherwise, use the manifolds that are on the van already, and get your exhaust built around that, and you will already have your 02 sensor.

Other than the VSS and 02 sensor, the rest of the sensors should already be installed on the engine. Simply take your time removing everything from the van, don't cut any wires, and you'll be fine. If you come across someplace where you feel you cannot get wires out without cutting them, trace them back to the ECM, put some tape around them, mark what pin they came from, then remove them from the ECM connector, and pull it out wire by wire. Pay careful attention to how everything was hooked up, and you will find that it is mostly a plug and play matter, less having to splice in a few power lines from an aftermarket fuse box (the 92ish Caprice / Buick LeSabres have a very neat fuse box that works very well for this)

I have a 1972 chevy truck and want to keep the manual trans. that is already behind it now cause it has the good np 205 transfer case and also i don't care about the van it was smashed so i can cut the firewall or fabicate it to get the wires out in one shot