IEBSBL,
Don't have Ryan Howards 60 time. They hardly ever run it after turning pro. However the PG site has many MLB players profiles from when they were in high school and most will show their top 60 time. Typically 1B run the 60 between 7.0 and 7.5 with some higher than 7.5.
Here are a few firstbasemen...
Prince Fielder ran 7.17 when he was in high school.
Prince FielderJoey Votto ran 7.11
Joey VottoIke DavisEric HosmerGaby SanchezFreddie FreemanHave to keep in mind that many "large body" guys actually slow down as they get older. I don't know this, but would guess that Paul Konerko would be lucky to break 8 flat.