Engine swap 4.3tbi to a 5.7 TBI HELP!!!!

[Hampin]

Good evening my name is hampin I am new to this site. I have a 4 month project on my hands and I have lost about all my hair. I left the old wiring harness in and changed the computer that was with the 5.7. Then I went to test drive it. It felt it was in gear with emergency brake on. I had no reverse. I also changed oil pump and motor before putting in and I have no oil pressure or oil in top half of motor. Is there anyone that has done the engine swap that has any suggestions for me. I would like to keep my last couple strings of hair. Ty