Could the radiators that were used in the garage on the Lexington project be used as a replacement for typical fin-tube baseboards? What is the benefit of using them?
I'm not familiar with the cast iron rads in this project, but generally speaking there are advantages & disadvantages to using cast iron rads in place of baseboard; cast iron rads these days are considered "old hat" because of some of their aspects: a) they're VERY heavy--a 5' cast iron rad weighs hundreds of pounds & you're asking for a hernia if you try to move one--this task should be left to professional movers; b) they often develop rust & can leak at their numerous seams as they age; c) however, cast iron rads have a much higher heat output (measured in btu's/hr).
There are ways to calculate how much heat in btu's/hour you need for a certain room dimension & this has to be done before installing cast iron rads, baseboard, or any other type of convector---Google "calculating radiator/baseboard heat btu output for a room".
Although cast iron rads are now considered "old fashioned", many people who own them wouldn't part with them because of their high heat output & their ability to remain hot long after the boiler has shut down & the hot water stops circulating thru them.