"69 455 for a '77 403

Im in the process of rebuilding an Olds 455 to replace my olds 403. It is in a '77 Olds 98 Regency and I could use some advice. I realize that this is not a common project and I need to know if anyone has done it.
1.Will my 403 motormounts fit my '69 455?
2.Will my 455 bolt up to my stock auto tranny?
If there are any tips for me, please let me know.

The tranny will bolt up, no problem. I can't remember on the mounts for the motor since I've not owned an Olds since the 70's.
I think they are the same but I am not sure.

how much punnishment will that poor tranny take in a 4000 pound car? I hope lots!