Here is a short poem read at the funeral of a dear Native friend of mine.
Perhaps it will fit with your fathers life on this earth or maybe it won't be appropriate. Not knowing anything about him nor what you are looking for I will offer this to you as a possibility. You may edit it to suit the man you loved and the man that loved you.
And I like it. Kinda fits with the free spirit in me, anyway.

Do not stand at my grave and weep
I am not there. I do not sleep.
I am a thousand winds that blow.
I am the diamond glints on snow.
I am the sunlight on ripened grain.
I am the gentle autumn's rain.

When you awaken in the morning's hush,
I am the swift uplifting rush
of quiet birds in circled flight.
I am the soft stars that shine at night.

Don't stand at my grave and cry
I am not there.
I did not die.

Love & Peace in the days ahead Bainsbane
MHW