We have an older house with a few hot water radiators in places we'd rather
put furniture. I'd like to replace a few of them with baseboard heat. We
have a single pipe system with each radiator fed off the "main" line and a
circulation pump. The boiler runs about 170F.

This seems to me to be a relatively simple matter of properly sizing the
baseboard and re-piping, but I'm always underestimating these things. Can
anyone offer some advice? Is there a preference for cast-iron versus
fin-tube baseboard units? Is there a simple way to predict baseboard size
from radiator size?

Thanks,
Tom