Paul wrote at 1 Corinthians 15:3-4: "For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures; and that he was buried, and that he rose again the third day according to the scriptures."
Matthew 12:40 has Jesus saying: “just as Jonah was three days and three nights in the belly of the great fish, so will the Son of Man be three days and three nights in the heart of the earth”
Jesus wasn't in paradise on his death. He was in the grave, as Paul wrote "according to the Scriptures." Ergo, the proper coma placement is: "Truly, I tell you today," not "I tell you, today."
The ἀμήν (amen, truly, verily) at Luke 23:43 indicates a fixed, firm pronouncement. There is no thought of: "Okay this is truth, but I might lie to you later."