Want to originate conventional conforming mortgage loans that stay in your servicing portfolio longer and secondary market investors are likely to pay up for? Look for borrowers with relatively lower credit scores and higher loan-to-value ratios. Thanks to new loan-characteristics disclosures being made by Fannie Mae and Freddie Mac about their mortgage pass-through securities, Wall Street investment bankers are drawing a more accurate bead on which loans are most likely to prepay in the