The problem is, you don't know what you'd need to know to make these sorts of calculations meaningful - nobody does. And your estimates are basically pulled straight out of your hat. Of the vast ocean of possible chains, you haven't got a clue how many of them are viable self-replicators, nor do you have any idea what a real minimum length for a viable self-replicator might be. There exist self-replicating polypeptides that are a mere 32 amino acids in length, so how on earth can you justify setting a minimum viable length of 29,000,000 nucleotides? You can't, and it's as simple as that.
longshadow sent me over here to see this. You have done quite well, certainly better than I could. The only difference is that i would have said "why bother"?
Let him stir the pot; it won't make a bit of difference. For the reasonable creationoids out there, they must be thinking exactly what the "reasonable" democrats are now thinking about their party leader.
"Why bother?" may be the only sensible answer ;)