[rmath]

Ray, you have the answer to your question in your records.
Your win percentages by rank gives you your answer.
Example: top pick 34% = 2/1 minimum to break even.
2nd pick 23% = 7/2 minimum to break even

your 5th horse at 5% = 20/1 minimum
Some authors say you should have at least a 50% overlay in order to make a bet.
others say it should be higher.

As for paceline selection FTLs guidelines are a very good way to go.
Personally I use the best of the last 3 COMPARABLE for each of my contenders.
Either of these will get you a high percentage of winners in your top 4 or 5 contenders.
From your records I am making the assumption that you are getting around 80 to 85% winners in your top 5.
My suggestion would be to work on your pacelines and try to get a few more of your 3rd, 4th, and 5th horses to move up into your top 2 or 3.
From your post this would be my suggestion.
I hope this will be of some help to you.

PS: If you would like to discuss any of this, feel fre to pm me and we can get together on skype.
rmath