I'm not a Bench fan, but play McCovey every day at Baker and pickup a Burns type to platoon at a pitchers park against LHs. Minch/Johnson would be a better 1B platoon IMHO.
I do not have much experience with Jack Clark, but his SLG against LHs is pretty low, $10M for high OBP seems steep to me.
It seems to me from looking at Mincher's card is that unless he is in a HR park he just does not get many hits. I think his production will be dead in a non HR park. I wanted Cash but lost him in the draft.
It totally depends on what the other parks in your div are, and how many LHP your opponents are starting. If your face move than 1/3 LHP, McCovey will be a big waste of cash. I love Clark's production, but he always seems to be hurt for me.