Looking for help on a few things. 12587603

I have a 12579405 which I plan on overwriting with 12587603 (I am hoping this is possible?) I am trying to learn myself, but don't really have months on months to figure everything out. I am wanting to make the computer stay in open loop(It's for a derby car, o2 sensors don't have time to correctly read to adjust fuel, ect.), I am also trying to keep the computer from going into limp mode when it gets to hot, deleting MAF sensor if possible? It is deleted on my 99 chevy lumina tuned PCM, figured it might be possible? Also, 4.8 engine that I am putting a TH375 behind it, is there anything in the tuning that needs to be changed to suffice for that transmission, or will it do just fine? I am making a simplified harness aswell. Honestly dont care if I brick the PCM, I will just go get another from the U-Pull it yard. Any help would be great, I am open to all opinions and knowledge.Attachment 16858