HELP!! 2008 4.3 to 4.8 swap still wont crank after vats delete

ok customer has a 2008 Silverado 4.3 truck converted it to a 4.8. They swapped the harness, computer, column and bcm I deleted the vats and I did write entire still didn't work. Even b4 tuning reduce engine power light was on. there is no power to the fuel pump the harness doesn't look like it had a fcm to it so I don't know if that would be the issue or not. you can straight wire the fuel pump and you can here it kick on not enough to crank it tho. I have disabled everything on the security side that could hold it back unfortunately I cant get paid if it don't crank. Any knowledge would help never ran into this issue.

trouble codes?

Whatever is wrong with the throttle is causing the no-start. Ignore everything else until you can get the pedal to control the TB with key-on.

wish I would of wrote down the codes it had. Had a code for key but the key was for the column they took. I think it has something to do with the fcm. I read that it can be bypassed but you have to use aftermarket fuel pump. im catching up with the guy this weekend to see what else they may have done.